skybox.cpp

   1 #include "shapes.hpp"
   2 #include "skybox.hpp"
   3 #include <glm/gtc/type_ptr.hpp>
   4
   5 GLuint setupCubeVertices(GLuint progId, bool reverse = false);
   6
   7 Skybox::Skybox(const Image img): program("skyboxvert.glsl", "skyboxfrag.glsl") {
   8         Program equiProg("skyboxvert.glsl", "equirectangularfrag.glsl");
   9         glUseProgram(equiProg.progId);
  10
  11         GLuint allTexIds[3];
  12         glGenTextures(3, allTexIds);
  13         hdrTexId = allTexIds[0], cubemapTexId = allTexIds[1], irradianceTexId = allTexIds[2];
  14
  15         glBindTexture(GL_TEXTURE_2D, hdrTexId);
  16
  17         glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16, img.width(), img.height(), 0, GL_RGB, GL_UNSIGNED_SHORT, (unsigned short*)img.data());
  18
  19         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  20         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  21         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  22         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  23
  24         // generate framebuffers to store cubemap in
  25         GLuint captureFBO, captureRBO;
  26         glGenFramebuffers(1, &captureFBO);
  27         glGenRenderbuffers(1, &captureRBO);
  28
  29         glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
  30         glBindRenderbuffer(GL_RENDERBUFFER, captureRBO);
  31         glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 512, 512);
  32         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, captureFBO);
  33
  34         // setup cubemap texture
  35         glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexId);
  36         for (GLuint i = 0; i < 6; i++)
  37                 glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 512, 512, 0, GL_RGB, GL_FLOAT, nullptr);
  38         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  39         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  40         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
  41         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  42         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  43
  44         // generate vertices
  45         setupCubeVertices(equiProg.progId);
  46
  47         // render the cube
  48         glm::mat4 captureProj = glm::perspective(glm::radians(90.f), 1.f, 0.1f, 10.f);
  49         glm::mat4 captureViews[] = {
  50                 glm::lookAt(glm::vec3(0, 0, 0), glm::vec3( 1,  0,  0), glm::vec3(0, -1,  0)),
  51                 glm::lookAt(glm::vec3(0, 0, 0), glm::vec3(-1,  0,  0), glm::vec3(0, -1,  0)),
  52                 glm::lookAt(glm::vec3(0, 0, 0), glm::vec3( 0,  1,  0), glm::vec3(0,  0,  1)),
  53                 glm::lookAt(glm::vec3(0, 0, 0), glm::vec3( 0, -1,  0), glm::vec3(0,  0, -1)),
  54                 glm::lookAt(glm::vec3(0, 0, 0), glm::vec3( 0,  0,  1), glm::vec3(0, -1,  0)),
  55                 glm::lookAt(glm::vec3(0, 0, 0), glm::vec3( 0,  0, -1), glm::vec3(0, -1,  0))
  56         };
  57
  58         glUniform1i(glGetUniformLocation(equiProg.progId, "equirectangularMap"), 0);
  59         glUniformMatrix4fv(glGetUniformLocation(equiProg.progId, "projection"), 1, GL_FALSE, glm::value_ptr(captureProj));
  60         glActiveTexture(GL_TEXTURE0);
  61         glBindTexture(GL_TEXTURE_2D, hdrTexId);
  62
  63         glViewport(0, 0, 512, 512);
  64         glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
  65         for (GLuint i = 0; i < 6; i++) {
  66                 glUniformMatrix4fv(glGetUniformLocation(equiProg.progId, "view"), 1, GL_FALSE, glm::value_ptr(captureViews[i]));
  67                 glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, cubemapTexId, 0);
  68                 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  69                 glDrawArrays(GL_TRIANGLES, 0, 36);
  70         }
  71
  72         // setup irradiance map texture
  73         glBindTexture(GL_TEXTURE_CUBE_MAP, irradianceTexId);
  74         for (GLuint i = 0; i < 6; i++)
  75                 glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 32, 32, 0, GL_RGB, GL_FLOAT, nullptr);
  76         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  77         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  78         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
  79         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  80         glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  81
  82         // bind framebuffers for rendering irradiance map into
  83         glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
  84         glBindRenderbuffer(GL_RENDERBUFFER, captureRBO);
  85         glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 32, 32);
  86
  87         Program irradianceProg("skyboxvert.glsl", "irradiancefrag.glsl");
  88         glUseProgram(irradianceProg.progId);
  89         glUniform1i(glGetUniformLocation(irradianceProg.progId, "environmentMap"), 0);
  90         glUniformMatrix4fv(glGetUniformLocation(irradianceProg.progId, "projection"), 1, GL_FALSE, glm::value_ptr(captureProj));
  91         glActiveTexture(GL_TEXTURE0);
  92         glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexId);
  93
  94         // generate vertices
  95         setupCubeVertices(irradianceProg.progId);
  96
  97         // render irradiance map
  98         glViewport(0, 0, 32, 32);
  99         glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
 100         for (GLuint i = 0; i < 6; i++) {
 101                 glUniformMatrix4fv(glGetUniformLocation(irradianceProg.progId, "view"), 1, GL_FALSE, glm::value_ptr(captureViews[i]));
 102                 glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, irradianceTexId, 0);
 103                 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 104                 glDrawArrays(GL_TRIANGLES, 0, 36);
 105         }
 106
 107         // switch back to regular skybox shader
 108         glUseProgram(program.progId);
 109         glDepthFunc(GL_LEQUAL);
 110
 111         // reverse so facing inside out
 112         vao = setupCubeVertices(program.progId, true);
 113
 114         // restore default framebuffer
 115         glBindFramebuffer(GL_FRAMEBUFFER, 0);
 116 }
 117
 118 void Skybox::draw(glm::mat4 proj, glm::mat4 view) const {
 119         glUseProgram(program.progId);
 120
 121         glBindVertexArray(vao);
 122
 123         GLuint projLoc = glGetUniformLocation(program.progId, "projection");
 124         glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(proj));
 125
 126         GLuint viewLoc = glGetUniformLocation(program.progId, "view");
 127         view = glm::mat4(glm::mat3(view));
 128         glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
 129
 130         glActiveTexture(GL_TEXTURE0);
 131         glBindTexture(GL_TEXTURE_CUBE_MAP, irradianceTexId);
 132         glDrawArrays(GL_TRIANGLES, 0, 36);
 133
 134         if (glGetError()) exit(1);
 135 }
 136
 137 GLuint setupCubeVertices(GLuint progId, bool reverse) {
 138         GLuint vao;
 139         glGenVertexArrays(1, &vao);
 140         glBindVertexArray(vao);
 141
 142         GLuint vbo;
 143         glGenBuffers(1, &vbo);
 144
 145         auto vertices = cube();
 146
 147         if (reverse)
 148                 std::reverse(vertices.begin(), vertices.end());
 149
 150         glBindBuffer(GL_ARRAY_BUFFER, vbo);
 151         glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(glm::vec3), &vertices[0], GL_STATIC_DRAW);
 152
 153         GLuint posLoc = glGetAttribLocation(progId, "pos");
 154         glEnableVertexAttribArray(posLoc);
 155         glVertexAttribPointer(posLoc, 3, GL_FLOAT, GL_FALSE, 0, 0);
 156
 157         return vao;
 158 }