APIs for initializing Tessellation Stages.While software tessellation can be done, tessellation implemented by hardware can generate an incredible amount of visual detail (including support for displacement mapping) without adding the visual detail to the model sizes and paralyzing refresh rates. Tessellation tiles (or breaks up) high-order surfaces into suitable structures for rendering.īy implementing tessellation in hardware, a graphics pipeline can evaluate lower detail (lower polygon count) models and render in higher detail. The Direct3D 11 runtime supports three new stages that implement tessellation, which converts low-detail subdivision surfaces into higher-detail primitives on the GPU. GLuint shader = glCreateShader (.) // Get strings for glShaderSource. This is done with a particular call to glGetShaderiv: Shader compilation failure is not an OpenGL Error you need to check for it specifically. Once shader strings have been set into a shader object, it can be compiled with this function:Ĭompilation may or may not succeed. If you pass NULL, then OpenGL will assume all of the strings are NULL-terminated and will therefore compute the length in the usual way. This allows you to use non-NULL-terminated strings. These are the lengths of the corresponding strings in the string array. The length can be either NULL or an array of count integers. This makes it easy for the user to load most of a shader from a file, but to have a standardized preamble that is prepended to some group of shaders. When the shader is compiled, it will be compiled as if all of the given strings were concatenated end-to-end. OpenGL will copy these strings into internal memory. count is the number of individual strings. Any previously stored strings are removed. This function takes the array of strings, given by string and stores it into shader. Void glShaderSource(GLuint shader, GLsizei count, const GLchar ** string, const GLint * length) Once you have a shader object, you will need to give it the actual text string representing the GLSL source code. Note that the control and evaluation shaders require GL 4.0 (or ARB_tessellation_shader), and the compute shader requires GL 4.3 (or ARB_compute_shader). The shader type must be one of GL_VERTEX_SHADER, GL_TESS_CONTROL_SHADER, GL_TESS_EVALUATION_SHADER, GL_GEOMETRY_SHADER, GL_FRAGMENT_SHADER, or GL_COMPUTE_SHADER. This creates an empty shader object for the shader stage given by given shaderType. GLuint glCreateShader(GLenum shaderType) To create a shader object, you call this function: The first step is to create shader objects for each shader that you intend to use and compile them. To get the executable program object, one or more shader objects must be linked together. With this method of program creation, shader text is first fed through a compiler, thus producing a shader object. To get the executable code, one or more object files must be linked together. C/C++ text is first fed through a compiler, thus producing an object file. This two-stage compilation process mirrors the standard compile/link setup for C and C++ source code. Building programs that contain multiple shader stages requires a two-stage compilation process.
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