CN112750191B - Method for manufacturing soft shadow in real-time rendering - Google Patents

Abstract

The invention relates to a method for making soft shadow in real-time rendering, which relates to the technical field of image processing and solves the problems that most of soft shadow generated by the prior method has poor quality or has high requirement on hardware and is difficult to be directly applied in games; giving an ID for each model, and rendering to a pickup frame buffer; rendering the original shadow to obtain an unoptimized shadow; and for the original shadow, carrying out horizontal Gaussian blur and vertical Gaussian blur according to the pickup frame buffer, synthesizing to obtain an optimized shadow, and on the basis of rendering the pickup frame buffer, softening the hard shadow by using the two-dimensional Gaussian blur step by step. With this method, high quality shadows can be generated in a shorter time.

Description

A method for making soft shadows in real-time rendering

Technical field

The invention relates to the technical field of image processing, and in particular to a method for producing soft shadows in real-time rendering.

Background technique

The recognition of different objects in the game usually requires the help of picking up the frame buffer. Shadow Mapping is commonly used in games to achieve soft shadow effects. The commonly used method is: high-precision super sampling at the shadow boundary. This is why soft shadows consume a lot of system resources, so this method is very difficult for the hardware. The requirements are higher. In the case of poor hardware conditions, it is more difficult to generate high-efficiency soft shadows.

Most of the soft shadows generated by existing methods are of poor quality or have high hardware requirements, making them difficult to apply directly in games. OpenGL (Open Graphics Library, open graphics library or open graphics library) is a cross-language and cross-platform application programming interface (API) used to render 2D and 3D vector graphics. This interface consists of nearly 350 different function calls used to draw everything from simple graphics bits to complex three-dimensional scenes. OpenGL is commonly used in CAD, virtual reality, scientific visualization programs, and video game development.

Shader is an editable program used to implement image rendering and replace the fixed rendering pipeline. Among them, the Vertex Shader is mainly responsible for the calculation of the geometric relationships of vertices, etc., and the Pixel Shader is mainly responsible for the calculation of the source color, etc.

The recognition of different objects in the game usually requires the help of picking up the frame buffer. Rendering the pickup framebuffer is expensive and has a single purpose.

Contents of the invention

In order to solve the problem that most of the soft shadows generated by existing methods are of poor quality or have high hardware requirements and are difficult to be directly applied in games, the present invention provides a method for making soft shadows in real-time rendering.

A method for making soft shadows in real-time rendering, which is implemented by the following steps:

Step 1. Initialize the OpenGL device and load the 3D model that needs to render shadows;

Step 2: Set a specific and unique ID for each model and render it to the pickup frame buffer;

Step 3: Directly render the original shadow to obtain an unoptimized shadow;

Step 4: Perform two-step Gaussian blur on the unoptimized shadow based on the picked frame buffer, including horizontal Gaussian blur based on the picked frame buffer and vertical Gaussian blur based on the picked frame buffer;

Step 5: Combine the results of Step 2 and Step 4 to obtain optimized shadows.

Beneficial effects of the present invention:

1. The present invention can realize the production of soft shadows and improve resource utilization by utilizing the picked-up frame buffer.

2. The present invention uses a step-by-step two-dimensional Gaussian Blur (Two Pass Gaussian Blur) based on the picked frame buffer (3D Picking Texture) obtained by rendering to achieve softening of hard shadows. Using this method, high-quality shadows can be generated in less time.

Description of the drawings

Figure 1 is a flow chart of a method for producing soft shadows in real-time rendering according to the present invention;

Figure 2 shows the rendering of the picked frame buffer;

Figure 3 shows the original shadow rendering;

Figure 4 shows the optimized shadow rendering.

Detailed ways

This embodiment, a method for making soft shadows in real-time rendering, is described with reference to Figures 1 to 4. The method is implemented by the following steps:

Step S1, use OpenGL rendering, initialize the OpenGL device, and load the model;

Initialize OpenGL, load the model into Vertex Array Object (VAO), Vertex Buffer Object (VBO), Index Buffer Object (IBO), and generate a pickup frame buffer.

Step S2: Set a specific and unique ID for each model and render it to the pickup frame buffer;

The unique ID of each model in the rendered pickup frame buffer is rendered into the frame buffer (Frame BufferObject) as a three-dimensional vector.

Step S3: Directly render the original shadow to obtain an unoptimized shadow;

Step S4: Perform two-step Gaussian blur on the original shadow according to the picked-up frame buffer;

Two-dimensional Gaussian blur is used to split the two-dimensional Gaussian blur into two steps, which is more efficient than directly using the two-dimensional Gaussian Convolution Kernel.

Step S5: Perform horizontal Gaussian blur according to the picked-up frame buffer;

Step S6: Perform vertical Gaussian blur according to the picked frame buffer;

According to the frame buffer picked up in step S2, the blurring process of distribution will not affect other objects. It will be judged during rendering. If other objects (with different ids) are rendered, the rendering will be stopped so that the blurred shadows are constrained to the same object. on objects.

The key to judging different IDs is to judge different objects by comparing the distance between the two IDs.

In this implementation, the graphics library used is OpenGL, but the implementation method is not limited to OpenGL. Using the same rendering pipeline, with slight improvements, it can be used in other graphics libraries such as Direct3D and Metal, as well as in the shader design of game engines such as Unity3D and Unreal. It can be easily ported to Windows, Android, IOS and other platforms.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-mentioned embodiments only express several implementation modes of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (2)

1. A method for producing soft shadows in real-time rendering, comprising the steps of:

initializing OpenGL equipment, and loading a 3D model needing shadow rendering;

loading a 3D model to the vertex group object, the vertex buffer object, and the index buffer object to generate a pickup frame buffer;

setting a specific unique ID of each model, and rendering to a pickup frame buffer;

step three, directly rendering an original shadow to obtain an unoptimized shadow;

step four, performing two-step Gaussian blur on the non-optimized shadow according to the picked-up frame buffer, wherein the two-step Gaussian blur comprises horizontal Gaussian blur according to the picked-up frame buffer and vertical Gaussian blur according to the picked-up frame buffer;

in the process of carrying out Gaussian blur in the horizontal direction and Gaussian blur in the vertical direction, judging according to the pickup frame buffer in the second step during rendering, and stopping rendering when other objects are rendered, so that blurred shadows are constrained on the same object;

judging whether the two objects are the same object by comparing the distances of the IDs of the two objects, and judging the two objects as different objects when the Euclidean distance of the IDs of the two objects is greater than a certain threshold value;

and step five, synthesizing the results of the step two and the step four to obtain the optimized shadow.

2. The method for producing soft shadows in real-time rendering according to claim 1, wherein: in the second step, the unique ID of each model of the rendered pickup frame buffer is rendered into the frame buffer as a three-dimensional vector.