理解OpenGLSuperbible7-GSCulling

2019-11-09 18:34:10

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#include "GLContext.h"#include <GL/gl.h>#include "common/vmath.h"#include "common/object.h"class GSCullingApp : public GLapplication{ void init() { static const char title[] = "OpenGL SuperBible - Geometry Shader Culling"; GLApplication::init(); memcpy(mInfo.title, title, sizeof(title)); } virtual void startup() { static const char * vs_source[] = { "#version 410 core /n" " /n" "// Incoming per vertex... position and normal /n" "layout (location = 0) in vec4 vVertex; /n" "layout (location = 1) in vec3 vNormal; /n" " /n" "out Vertex /n" "{ /n" " vec3 normal; /n" " vec4 color; /n" "} vertex; /n" " /n" "uniform vec3 vLightPosition = vec3(-10.0, 40.0, 200.0); /n" "uniform mat4 mvMatrix; /n" " /n" "void main(void) /n" "{ /n" " // Get surface normal in eye coordinates /n" " vec3 vEyeNormal = mat3(mvMatrix) * normalize(vNormal); /n" " /n" " // Get vertex position in eye coordinates /n" " vec4 vPosition4 = mvMatrix * vVertex; /n" " vec3 vPosition3 = vPosition4.xyz / vPosition4.w; /n" " /n" " // Get vector to light source /n" " vec3 vLightDir = normalize(vLightPosition - vPosition3); /n" " /n" " // Dot PRoduct gives us diffuse intensity /n" " vertex.color = vec4(0.7, 0.6, 1.0, 1.0) * abs(dot(vEyeNormal, vLightDir)); /n" " /n" " gl_Position = vVertex; /n" " vertex.normal = vNormal; /n" "} /n" }; static const char * gs_source[] = { "#version 410 core /n" " /n" "layout (triangles) in; /n" "layout (triangle_strip, max_vertices = 3) out; /n" " /n" "in Vertex /n" "{ /n" " vec3 normal; /n" " vec4 color; /n" "} vertex[]; /n" " /n" "out vec4 color; /n" " /n" "uniform vec3 vLightPosition; /n" "uniform mat4 mvpMatrix; /n" "uniform mat4 mvMatrix; /n" " /n" "uniform vec3 viewpoint; /n" " /n" "void main(void) /n" "{ /n" " int n; /n" " /n" " vec3 ab = gl_in[1].gl_Position.xyz - gl_in[0].gl_Position.xyz; /n" " vec3 ac = gl_in[2].gl_Position.xyz - gl_in[0].gl_Position.xyz; /n" " vec3 normal = normalize(cross(ab, ac)); /n" " vec3 transformed_normal = (mat3(mvMatrix) * normal); /n" " vec4 worldspace = /* mvMatrix * */ gl_in[0].gl_Position; /n" " vec3 vt = normalize(viewpoint - worldspace.xyz); /n" " /n" " if (dot(normal, vt) > 0.0) { /n" " for (n = 0; n < 3; n++) { /n" " gl_Position = mvpMatrix * gl_in[n].gl_Position; /n" " color = vertex[n].color; /n" " EmitVertex(); /n" " } /n" " EndPrimitive(); /n" " } /n" "} /n" }; static const char * fs_source[] = { "#version 410 core /n" " /n" "in vec4 color; /n" " /n" "out vec4 output_color; /n" " /n" "void main(void) /n" "{ /n" " output_color = color; /n" "} /n" }; program = glCreateProgram(); GLuint vs = glCreateShader(GL_VERTEX_SHADER); glShaderSource(vs, 1, vs_source, NULL); glCompileShader(vs); GLuint gs = glCreateShader(GL_GEOMETRY_SHADER); glShaderSource(gs, 1, gs_source, NULL); glCompileShader(gs); GLuint fs = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(fs, 1, fs_source, NULL); glCompileShader(fs); glAttachShader(program, vs); glAttachShader(program, gs); glAttachShader(program, fs); glLinkProgram(program); mv_location = glGetUniformLocation(program, "mvMatrix"); mvp_location = glGetUniformLocation(program, "mvpMatrix"); viewpoint_location = glGetUniformLocation(program, "viewpoint"); object.load("media/objects/dragon.sbm"); glDisable(GL_CULL_FACE); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); } virtual void render(double currentTime) { static const GLfloat black[] = { 0.0f, 0.0f, 0.0f, 1.0f }; static const GLfloat one = 1.0f; float f = (float)currentTime; glViewport(0, 0, mInfo.windowWidth, mInfo.windowHeight); glClearBufferfv(GL_COLOR, 0, black); glClearBufferfv(GL_DEPTH, 0, &one); glUseProgram(program); vmath::mat4 proj_matrix = vmath::perspective(50.0f, (float)mInfo.windowWidth / (float)mInfo.windowHeight, 0.1f, 1000.0f); vmath::mat4 mv_matrix = vmath::translate(0.0f, 0.0f, -20.0f) * vmath::rotate((float)currentTime * 5.0f, 0.0f, 1.0f, 0.0f) * vmath::rotate((float)currentTime * 100.0f, 1.0f, 0.0f, 0.0f); glUniformMatrix4fv(mvp_location, 1, GL_FALSE, proj_matrix * mv_matrix); glUniformMatrix4fv(mv_location, 1, GL_FALSE, mv_matrix); GLfloat vViewpoint[] = { sinf(f * 2.1f) * 70.0f, cosf(f * 1.4f) * 70.0f, sinf(f * 0.7f) * 70.0f }; glUniform3fv(viewpoint_location, 1, vViewpoint); object.render(); } virtual void shutdown() { object.free(); glDeleteProgram(program); }private: GLuint program; GLint mv_location; GLint mvp_location; GLint viewpoint_location; Object object;};DECLARE_MAIN(GSCullingApp)