Subsurface scattering simulation method and device based on model space
By performing gradient masking and pose conversion in the model space, the problem of surface scattering calculation of mobile terminals last time is solved, the balance of reality and performance is achieved, and the user experience is improved.
Patent Information
- Application Number
- CN202411323938.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2024-12-27
AI Technical Summary
The prior art is difficult to support real subsurface scattering calculations on mobile terminals, resulting in a lack of realism and interactivity in the rendering effect and poor user experience.
By obtaining the vertex coordinates of the rendered object in the model space for linear interpolation, a gradient mask is obtained, and combined with the coordinate axis direction vector of the model space to convert it to the world space. The corresponding gradient mask and basic color are selected according to the current pose of the rendered object. Surface scattering simulation avoids complex real-time ray tracing calculations.
It creates a more realistic visual effect while maintaining a good performance balance, suitable for three-dimensional applications on mobile terminals.
Smart Images
Figure CN119206034A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of computer graphics rendering, and in particular to a subsurface scattering simulation method and apparatus based on model space, a computing device, and a computer-readable storage medium. Background Art
[0002] Subsurface scattering (SSS) is a phenomenon that simulates the propagation and scattering of light under the surface of an object. This phenomenon usually occurs when there is one or more layers of non-uniform media under the surface of the object, such as skin, marble, hair, etc. Subsurface scattering can increase the realism and texture of the object, making it look more realistic. However, real subsurface scattering requires a lot of calculations and is difficult to support on ordinary mobile terminals. Therefore, the conventional practice is to draw the scattering effect directly on the map, resulting in a lack of realism and interactivity in the rendering effect, and a poor user experience. Summary of the invention
[0003] In view of this, embodiments of the present application provide a subsurface scattering simulation method and apparatus based on a model space, a computing device, and a computer-readable storage medium to address the technical deficiencies in the prior art.
[0004] According to a first aspect of an embodiment of the present application, a subsurface scattering simulation method based on a model space is provided, comprising:
[0005] Obtain vertex coordinates of the rendering object in the model space, perform linear interpolation on the rendering object according to the relationship between the vertex coordinates, and obtain a gradient mask of the rendering object in different postures;
[0006] Convert the coordinate axis direction vector of the model space to the world space to obtain a first vector in the world space; obtain the current posture of the rendering object according to the first vector;
[0007] The corresponding gradient mask is selected according to the current posture of the rendering object, and the subsurface scattering simulation is completed in combination with the basic color of the rendering object.
[0008] According to a second aspect of an embodiment of the present application, a subsurface scattering simulation device based on a model space is provided, comprising:
[0009] A first calculation unit is used to obtain vertex coordinates of the rendering object in the model space, and perform linear interpolation on the rendering object according to the relationship between the vertex coordinates to obtain a gradient mask of the rendering object in different postures;
[0010] A conversion unit, used for converting the coordinate axis direction vector of the model space into the world space to obtain a first vector in the world space; and obtaining the current posture of the rendering object according to the first vector;
[0011] A determination unit, configured to obtain a current posture of the rendering object according to the first vector;
[0012] The second calculation unit is used to select the corresponding gradient mask according to the current posture of the rendering object, and complete the subsurface scattering simulation in combination with the basic color of the rendering object.
[0013] According to a third aspect of an embodiment of the present application, a computing device is provided, comprising a memory, a processor, and computer instructions stored in the memory and executable on the processor, wherein when the processor executes the instructions, the steps of the subsurface scattering simulation method based on model space are implemented.
[0014] According to a fourth aspect of an embodiment of the present application, a computer-readable storage medium is provided, which stores computer instructions, and when the instructions are executed by a processor, the steps of the subsurface scattering simulation method based on model space are implemented.
[0015] Through the method provided by the embodiment of the present application, when rendering an object in the shader, first obtain the coordinates of the object's vertices in the model space, perform interpolation calculations based on the positional relationship of the coordinates, and obtain the gradient color of the object in different postures; then obtain the posture of the object in the world space based on the coordinate system conversion relationship, and select the corresponding gradient color based on the current posture of the object to complete the subsurface scattering rendering effect. This solution combines model space position coordinates, world space transformation matrix and other data, and uses color gradient to simulate the subsurface transmission effect, avoiding complex real-time ray tracing calculations, creating a more realistic visual effect, while maintaining a better performance balance, and is suitable for three-dimensional applications on mobile terminals. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a structural block diagram of a computing device provided in an embodiment of the present application;
[0017] Figure 2 It is a flow chart of a subsurface scattering simulation method based on model space provided in an embodiment of the present application;
[0018] Figure 3 is a schematic diagram of vertex coordinates of a rendering object in a model space provided by an embodiment of the present application;
[0019] Figure 4a is a schematic diagram of a gradient color of a rendering object calculated according to vertex coordinates provided in an embodiment of the present application;
[0020] Figure 4b is another schematic diagram of a gradient color of a rendering object calculated according to vertex coordinates provided in an embodiment of the present application;
[0021] Figure 5a is a schematic diagram of determining the posture of a rendering object provided by an embodiment of the present application;
[0022] Figure 5b is another schematic diagram of determining the posture of a rendering object provided by an embodiment of the present application;
[0023] Figure 5c is another schematic diagram of determining the posture of a rendering object provided by an embodiment of the present application;
[0024] Figure 6 This is a schematic diagram of the effect of performing subsurface scattering simulation on a rendering object with different postures provided by an embodiment of the present application;
[0025] Figure 7 It is a structural schematic diagram of a subsurface scattering simulation device based on model space provided in an embodiment of the present application. DETAILED DESCRIPTION
[0026] Many specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application, so the present application is not limited by the specific implementation disclosed below.
[0027] The terms used in one or more embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit one or more embodiments of the present application. The singular forms of "a", "said" and "the" used in one or more embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in one or more embodiments of the present application refers to and includes any or all possible combinations of one or more associated listed items.
[0028] It should be understood that, although the terms first, second, etc. may be used to describe various information in one or more embodiments of the present application, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of one or more embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. Depending on the context, the word "if" as used herein may be interpreted as "in response to determination".
[0029] In the present application, a subsurface scattering simulation method and apparatus based on a model space, a computing device and a computer-readable storage medium are provided, which will be described in detail one by one in the following embodiments.
[0030] Figure 1The structure block diagram of a computing device 100 according to an embodiment of the present application is shown. The components of the computing device 100 include but are not limited to a memory 110 and a processor 120. The processor 120 is connected to the memory 110 via a bus 130, and the database 150 is used to store data.
[0031] The computing device 100 also includes an access device 140 that enables the computing device 100 to communicate via one or more networks 160. Examples of these networks include a public switched telephone network (PSTN), a local area network (LAN), a wide area network (WAN), a personal area network (PAN), or a combination of communication networks such as the Internet. The access device 140 may include one or more of any type of network interface (e.g., a network interface card (NIC)) whether wired or wireless, such as an IEEE 802.11 wireless local area network (WLAN) wireless interface, a World Wide Interoperability for Microwave Access (Wi-MAX) interface, an Ethernet interface, a universal serial bus (USB) interface, a cellular network interface, a Bluetooth interface, a near field communication (NFC) interface, and the like.
[0032] In one embodiment of the present application, the above components of the computing device 100 and Figure 1 Other components not shown in the figure may also be connected to each other, for example, via a bus. It should be understood that Figure 1 The computing device structure block diagram shown is only for the purpose of illustration, and is not intended to limit the scope of the present application. Those skilled in the art may add or replace other components as needed.
[0033] Computing device 100 may be any type of stationary or mobile computing device, including a mobile computer or mobile computing device (e.g., a tablet computer, a personal digital assistant, a laptop computer, a notebook computer, a netbook, etc.), a mobile phone (e.g., a smartphone), a wearable computing device (e.g., a smart watch, smart glasses, etc.), or other type of mobile device, or a stationary computing device such as a desktop computer or PC.
[0034] In the embodiments of the present application, Figure 2 A flow chart of a subsurface scattering simulation method based on model space provided by the present application is shown, including steps 202 to 206.
[0035] Step 202: acquiring vertex coordinates of the rendering object in the model space, performing linear interpolation on the rendering object according to the relationship between the vertex coordinates, and obtaining a gradient mask of the rendering object in different postures.
[0036] In this step, all vertex coordinates of the rendering object are obtained, and the vertex coordinates are determined according to the shape of the rendering object. For example, when the rendering object is a cuboid or a cube, it includes 8 vertices; when the rendering object is a triangular prism, it includes 6 vertices; when the rendering object is a pyramid, it includes 5 vertices.
[0037] Furthermore, linear interpolation is performed on the rendered object according to the relationship between the acquired vertex coordinates to obtain a gradient mask of the rendered object in different postures to simulate a scattering effect.
[0038] In a feasible implementation, specific vertex coordinates are selected as starting point coordinates according to different axial directions in the model space.
[0039] For example, when the rendered object is a cuboid and is in a lying position, Figure 3 As shown, the coordinates of vertices A and B are A(x, y, z) and B(x, y, z) respectively. According to the knowledge of three-dimensional coordinates, the x and z of vertices A and B are equal, and only the coordinate values on the Y axis are different. Therefore, when rendering in this posture, the coordinate points on the Y axis are used in the fragment shader to calculate the gradient mask of the rendered object:
[0040] float UpMask = smoothstep(y1, y2, posOS.y), where y1 and y2 are the Y coordinates of vertices A and B respectively, and posOS.y is the Y coordinate of the vertex of the rendered object in model space, thus obtaining Figure 4a Schematic gradient mask effect.
[0041] When the rendered object is a cuboid and is in a standing posture, the coordinates of its vertices B and C are B(x,y,z) and C(x,y,z) respectively. According to the knowledge of three-dimensional coordinates, the x and y values of vertices A and B are equal, and only the coordinate values on the Z axis are different. Therefore, when the rendering is in this posture, the coordinate points on the Z axis are used in the fragment shader to calculate the gradient mask of the rendered object:
[0042] half StandMask = smoothstep(z2,z3,posOS.z), where z2 and z3 are the Z coordinates of vertices B and C respectively, and posOS.z is the Z coordinate of the vertex of the rendered object in model space, thus obtaining Figure 4b Schematic gradient mask effect.
[0043] Similarly, according to the relationship between the coordinates of other vertices, the gradient mask of the rendered object in different postures can be obtained, which will not be described in detail here.
[0044] Step 204: Convert the direction vector in the model space to the world space to obtain the first vector in the world space; obtain the current pose of the rendering object according to the first vector.
[0045] First, in the vertex shader, transfer the direction vectors of each coordinate axis in the model space to the world space. For example, transfer the Y-axis and Z-axis direction vectors to the world space to distinguish different poses of the rendering object:
[0046] o.posDirY = mul(unity_ObjectToWorld, float3(0, 1, 0));
[0047] o.posDirZ = mul(unity_ObjectToWorld, float3(0, 0, 1));
[0048] Furthermore, in the fragment shader, normalize the converted vectors to limit the numerical range between 0 and 1. For example:
[0049] float3 posDirY = normalize(i.posDirY);
[0050] float3 posDirZ = normalize(i.posDirZ);
[0051] Further, distinguish the poses of the rendering object according to the normalized world space vectors.
[0052] In a feasible implementation, use the step function to judge the normalized world space vectors to obtain the current pose of the rendering object.
[0053] The definition of step(edge, x) is as follows:
[0054] float step(float edge, float x);
[0055] If x < edge, return 0.0;
[0056] If x >= edge, return 1.0.
[0057] Specifically, judge whether the rendering object is in the standing pose:
[0058] half isStand = step(0.99, posDirZ.y);
[0059] posDirZ.y is the projection of the Z-axis of the object on the Y-axis in the world space;
[0060] When posDirZ.y=1, posDirZ.y>0.99, the step function returns 1, that is, the posture flag isStand=1, which means that the Z axis of the rendering object is parallel to the Y axis of the world space and is in a standing posture.
[0061] Similarly, determine whether the rendered object is facing up:
[0062] half isUP=step(0.99,posDirY.y);
[0063] What is compared here is the y component of posDirY, that is, posDirY.y.
[0064] When posDirY.y=1, posDirY.y>0.99, the step function returns 1, that is, the posture flag isUP=1, indicating that the rendered object is facing up.
[0065] Similarly, determine whether the rendered object is in a back-facing posture:
[0066] half isBack=step(0.99,-posDirY.y);
[0067] When posDirY.y=-1, -posDirY.y>0.99, the step function returns 1, indicating that the back of the rendered object is facing upwards.
[0068] The posture distinction of all rendered objects is completed in the above way, such as Figure 5a As shown, the white area includes multiple rendered objects that are identified as standing; Figure 5b The middle white area includes multiple rendered objects identified as facing right-side up. Figure 5c The medium white area includes multiple rendered objects with their back faces facing upwards.
[0069] Those skilled in the art should know that the above-mentioned rendering object posture judgment algorithm is only an example, and its calculation method can be adjusted according to the specific three-dimensional scene, which will not be described in detail here.
[0070] Step 206: Select a corresponding gradient mask according to the current posture of the rendering object, and complete the subsurface scattering simulation in combination with the basic color of the rendering object.
[0071] In step 202, the gradient masks of the rendering object in different postures have been obtained. Therefore, in this step, the corresponding gradient mask is selected according to the current posture of the rendering object to complete the rendering effect of the subsurface scattering simulation.
[0072] Specifically, selecting a corresponding gradient mask according to the current posture of the rendering object includes, for example, when the current posture of the rendering object is standing, selecting a gradient mask StandMask corresponding to the standing posture;
[0073] Preferably, before completing the subsurface scattering simulation according to the gradient mask, further adjust the different brightness values of the rendered object in the gradient area to adjust the gradient effect, for example, in a standing posture:
[0074] half3 MJZStandAlbedo=lerp(MJZAlbedo*_frontDarkVal,MJZAlbedo*_frontLightVal,StandMask);
[0075] MJZAlbedo is the base color of the rendered object, _frontDarkVal and _frontLightVal are the values used to adjust the color;
[0076] The lerp function performs linear interpolation between the above two values according to StandMask to obtain the adjusted gradient effect MJZStandAlbedo.
[0077] Furthermore, based on the adjusted gradient effect, the color is adjusted again according to the posture of the rendering object to complete the final effect rendering, wherein the posture identifier of the rendering object is used as a mask, for example, an interpolation calculation is performed here:
[0078] MJZAlbedo = lerp (MJZAlbedo, MJZStandAlbedo, isStand); / / Rendering of standing posture
[0079] MJZAlbedo = lerp (MJZAlbedo, MJZUpAlbedo, isUp); / / Rendering facing up
[0080] MJZAlbedo = lerp (MJZAlbedo, MJZBackAlbedo, isBack); / / Rendering with the back side facing up
[0081] If the posture flag isStand of the current rendering object is equal to 1, the previous gradient effect MJZStandAlbedo will be applied for calculation.
[0082] For other rendering objects, such as the rendering object with the front side facing up or the back side facing up, the original color remains unaffected because its isStand posture identifier is 0; instead, the effect rendering is completed through its corresponding posture identifier. For example, for the rendering object with the back side facing up, its posture identifier isBack=1, so the effect rendering is completed according to the gradient effect MJZUpAlbedo, which will not be repeated here.
[0083] That is, in this way, the gradient colors of each pose rendering object are adjusted at the same time, completing the simulation of their subsurface scattering effects. Figure 6 As shown, the top of the rendered object in a standing posture is brighter and the sides gradually become darker; the top of the rendered object facing upward is brighter and the sides gradually become darker; and the top of the rendered object facing backward is dark and the sides gradually become darker.
[0084] In the above-mentioned embodiment of the present application, in order to efficiently realize the subsurface scattering rendering effect of the object on the mobile terminal without consuming too many hardware resources, when rendering the object in the shader, the coordinates of the object's vertices in the model space are first obtained, and interpolation calculations are performed according to the positional relationship of the coordinates to obtain the gradient color of the object in different postures; then the posture of the object in the world space is obtained according to the coordinate system conversion relationship, and the corresponding gradient color is selected according to the current posture of the object to complete the subsurface scattering rendering effect. This solution combines the model space position coordinates, the world space transformation matrix and other data, and uses the color gradient method to simulate the subsurface transmission effect, avoiding complex real-time ray tracing calculations, creating a more realistic visual effect, while maintaining a better performance balance, and is suitable for three-dimensional applications on mobile terminals.
[0085] Corresponding to the above method embodiment, the present application also provides an embodiment of a subsurface scattering simulation device based on a model space, such as Figure 7 As shown, the device comprises:
[0086] A first calculation unit is used to obtain vertex coordinates of the rendering object in the model space, and perform linear interpolation on the rendering object according to the relationship between the vertex coordinates to obtain a gradient mask of the rendering object in different postures;
[0087] A conversion unit, used for converting the coordinate axis direction vector of the model space into the world space to obtain a first vector in the world space; and obtaining the current posture of the rendering object according to the first vector;
[0088] A determination unit, configured to obtain a current posture of the rendering object according to the first vector;
[0089] The second calculation unit is used to select the corresponding gradient mask according to the current posture of the rendering object, and complete the subsurface scattering simulation in combination with the basic color of the rendering object.
[0090] The above is a schematic scheme of a subsurface scattering simulation device based on model space of this embodiment. It should be noted that the technical scheme of the subsurface scattering simulation device based on model space and the technical scheme of the subsurface scattering simulation method based on model space belong to the same concept, and the details of the technical scheme of the subsurface scattering simulation device based on model space that are not described in detail can all be referred to the description of the technical scheme of the subsurface scattering simulation method based on model space.
[0091] In one embodiment of the present application, a computing device is also provided, including a memory, a processor, and computer instructions stored in the memory and executable on the processor, wherein when the processor executes the instructions, the steps of the subsurface scattering simulation method based on the model space are implemented.
[0092] The above is a schematic scheme of a computing device of this embodiment. It should be noted that the technical scheme of the computing device and the technical scheme of the subsurface scattering simulation method based on the model space are of the same concept, and the details not described in detail in the technical scheme of the computing device can be referred to the description of the technical scheme of the subsurface scattering simulation method based on the model space.
[0093] An embodiment of the present application further provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the steps of the subsurface scattering simulation method based on the model space as described above.
[0094] The above is a schematic scheme of a computer-readable storage medium of the present embodiment. It should be noted that the technical scheme of the storage medium and the technical scheme of the subsurface scattering simulation method based on the model space described above belong to the same concept, and the details not described in detail in the technical scheme of the storage medium can be referred to the description of the technical scheme of the subsurface scattering simulation method based on the model space described above.
[0095] The above describes specific embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
[0096] The computer instructions include computer program codes, which may be in source code form, object code form, executable files or some intermediate forms, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.
[0097] It should be noted that, for the above-mentioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.
[0098] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0099] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The optional embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of the present application. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can understand and use the present application well. The present application is only limited by the claims and their full scope and equivalents.
Claims
1. A subsurface scattering simulation method based on model space, characterized in that: include: Obtain vertex coordinates of the rendering object in the model space, perform linear interpolation on the rendering object according to the relationship between the vertex coordinates, and obtain a gradient mask of the rendering object in different postures; Convert the coordinate axis direction vector of the model space to the world space to obtain a first vector in the world space; obtain the current posture of the rendering object according to the first vector; The corresponding gradient mask is selected according to the current posture of the rendering object, and the subsurface scattering simulation is completed in combination with the basic color of the rendering object.
2. The method according to claim 1, wherein: The linear interpolation of the rendered object according to the relationship between the vertex coordinates to obtain the gradient mask of the rendered object in different postures includes: Specific vertex coordinates are selected in the model space, and the coordinate points in the coordinate axis directions corresponding to different postures are used as inputs for linear interpolation in the fragment shader to calculate the gradient mask of the rendered object in different postures.
3. The method according to claim 1, wherein: The step of converting the coordinate axis direction vector of the model space to the world space to obtain the first vector in the world space includes: In the vertex shader, convert the axial direction vectors of each coordinate in the model space to the world space; The converted vector is normalized in the fragment shader to obtain the first vector.
4. The method according to claim 3, wherein: The obtaining the current posture of the rendering object according to the first vector comprises: The step function is used to judge each component of the first vector to obtain a current posture of the rendering object, where the current posture of the rendering object is expressed by a posture identifier.
5. The method according to claim 4, wherein: The step of selecting the corresponding gradient mask according to the current posture of the rendering object and completing the subsurface scattering simulation in combination with the basic color of the rendering object comprises: Obtaining a gradient mask, and adjusting different brightness values of the rendered object in the gradient area in combination with the gradient mask; The posture mark of the rendered object is used as a mask, and the final rendering effect is completed based on the adjusted gradient effect and the basic color of the rendered object.
6. A subsurface scattering simulation device based on model space, characterized in that: include: A first calculation unit is used to obtain vertex coordinates of the rendering object in the model space, and perform linear interpolation on the rendering object according to the relationship between the vertex coordinates to obtain a gradient mask of the rendering object in different postures; A conversion unit, used for converting the coordinate axis direction vector of the model space into the world space to obtain the first vector in the world space; A determination unit, configured to obtain a current posture of the rendering object according to the first vector; The second calculation unit is used to select the corresponding gradient mask according to the current posture of the rendering object, and complete the subsurface scattering simulation in combination with the basic color of the rendering object.
7. A computing device comprising a memory, a processor, and computer instructions stored in the memory and executable on the processor, characterized in that: When the processor executes the instructions, the steps of the method according to any one of claims 1 to 5 are implemented.
8. A computer-readable storage medium storing computer instructions, characterized in that: When the instruction is executed by a processor, the steps of the method described in any one of claims 1 to 5 are implemented.