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

Method for manufacturing soft shadow in real-time rendering

Technical Field

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

Background

The identification of different objects in a game is usually accomplished by means of a pick-up frame buffer. The soft Shadow effect is realized in a Shadow Mapping (Shadow Mapping) mode commonly used in games, and the method is generally adopted as follows: the method of performing high-precision supersampling at the shadow boundary is the reason that soft shadow consumes large system resources, so that the method has high requirement on hardware. And in the case of poor hardware conditions, the generation of high-efficiency soft shadows is difficult.

The soft shadows generated by the existing method are mostly poor in quality or high in hardware requirement, and are difficult to directly apply in games. OpenGL (Open Graphics Library, open graphics library or open graphics library) is used to render cross-language, cross-platform Application Programming Interfaces (APIs) for 2D, 3D vector graphics. This interface consists of nearly 350 different function calls, used to draw a scene from simple graphics bits to complex three dimensions. OpenGL is commonly used for CAD, virtual reality, scientific visualization programs, and electronic game development.

A Shader (loader) is used to implement image rendering, replacing the editable program of the fixed rendering pipeline. Wherein, the Vertex loader is mainly responsible for the calculation of the geometric relationship of the Vertex, and the Pixel loader is mainly responsible for the calculation of the patch source color, and the like.

The identification of different objects in a game is usually accomplished by means of a pick-up frame buffer. The overhead of rendering the pick-up frame buffer is not low, but single-purpose.

Disclosure of Invention

The invention provides a method for manufacturing soft shadows in real-time rendering, which aims to solve the problems that most soft shadows generated by the existing method are poor in quality or high in hardware requirement and difficult to directly apply in games.

A method for making soft shadow in real-time rendering is realized by the following steps:

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

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;

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

The invention has the beneficial effects that:

1. the invention can realize the manufacture of soft shadows by utilizing the picked frame buffer, thereby improving the utilization rate of resources.

2. The invention uses stepwise two-dimensional Gaussian blur (Two Pass Gaussian Blur) on the basis of the rendered pick-up frame buffer (3D Picking Texture) to soften the hard shadow. With this method, high quality shadows can be generated in a shorter time.

Drawings

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

FIG. 2 is a rendered pickup frame buffer effect diagram;

FIG. 3 is a rendered original shadow effect map;

fig. 4 is a graph of the optimized shadow effect.

Detailed Description

The present embodiment will be described with reference to fig. 1 to 4, which are a method for producing soft shadows in real-time rendering, comprising the steps of:

step S1, using OpenGL rendering, initializing OpenGL equipment and loading a model;

OpenGL is initialized, a model is loaded to a vertex group object (Vertex Array Object, VAO), a vertex buffer object (Vertex Buffer Object, VBO), an index buffer object (Indices Buffer Object, IBO), and a pick frame buffer is generated.

S2, setting a specific unique ID of each model, and rendering to a pickup frame buffer;

the rendered picked frame buffer the unique ID of each model is rendered into a frame buffer (Frame Buffer Object) as a three-dimensional vector.

S3, directly rendering the original shadow to obtain an unoptimized shadow;

s4, carrying out two-step Gaussian blur on the original shadow according to the picked frame buffer;

the two-dimensional Gaussian blur is split into two steps to be realized, and compared with the method of directly using a two-dimensional Gaussian convolution kernel (Gaussian Convolution Kernel), the method has higher efficiency.

S5, carrying out Gaussian blur in the horizontal direction according to the picked-up frame buffer;

s6, carrying out Gaussian blur in the vertical direction according to the picked frame buffer;

according to the pickup frame buffering of step S2, the blurring process performed by the distribution does not affect other objects, and the judgment is performed during rendering, and if other objects (with different ids) are rendered, the rendering is stopped, so that the blurred shadows are constrained on the same object.

The key of judging different ids is to judge different objects by comparing the distances of the two ids.

In the present embodiment, the graphics library used is OpenGL, but the implementation is not limited to OpenGL. The same rendering pipeline is used, and the method can be used for other graphic libraries such as Direct3D, metal and the like, and can also be used for the loader design of game engines such as Unity3D, unreal and the like by slightly improving the rendering pipeline. Can be conveniently transplanted to various platforms such as Windows, android, IOS and the like.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to 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.