skybox.cpp

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