海面模擬以及渲染（計算著色器、FFT、Reflection Matrix）
阿新 • • 發佈：2019-02-06
Update計算著色器程式碼：（基本上就是根據理論公式寫程式碼）GLfloat RandomUniform(const GLfloat start, const GLfloat end) { return ((GLfloat)rand() / (GLfloat)RAND_MAX) * (end - start) + start; } GLfloat RandomNormal(const GLfloat mean, const GLfloat standardDeviation) { GLfloat x1, x2; x1 = RandomUniform(GLUS_UNIFORM_RANDOM_BIAS, 1.0f - GLUS_UNIFORM_RANDOM_BIAS); x2 = RandomUniform(0.0f, 1.0f); return mean + standardDeviation * (sqrtf(-2.0f * logf(x1)) * cosf(2.0f * GL_PI * x2)); } GLfloat OceanMeshForGPU::PhillipsSpectrum(GLfloat A, GLfloat L, glm::vec2 waveDirection, glm::vec2 windDirection) { GLfloat k = glm::length(waveDirection); GLfloat waveDotWind = glm::dot(waveDirection, windDirection); if (L == 0.0f || k == 0.0f) { return 0.0f; } return A * expf(-1.0f / (k * L * k * L)) / (k * k * k * k) * waveDotWind * waveDotWind; } GLboolean OceanMeshForGPU::Init() { glm::vec3 lightDirection = { 0.5f, 1.0f, 1.0f }; glm::vec4 color = { 0.0f, 0.8f, 0.8f, 1.0f }; GLUSshape gridPlane; GLint i, k; glm::mat4 matrix = glm::mat4(); GLfloat* h0Data; GLint* butterflyIndices; GLfloat* butterflyIndicesAsFloat; glm::vec2 waveDirection; glm::vec2 windDirection = WIND_DIRECTION; GLfloat phillipsSpectrumValue; //通過項數計算出計算 FFT 的時候需要的迭代總次數 GLint steps = 0; GLint temp = N; while (!(temp & 0x1)) { temp = temp >> 1; steps++; } //宣告更新海面網格的計算著色器 g_computeUpdateHtProgram = new Shader("OceanUpdate.comp"); //宣告進行FFT的計算著色器 g_computeFftProgram = new Shader("OceanFFT.comp"); //宣告更新法線向量的計算著色器 g_computeUpdateNormalProgram = new Shader("OceanUpdateNormal.comp"); //宣告進行渲染的頂點和畫素著色器 g_program = new Shader("OceanGPU.vs", "OceanGPU.frag"); g_totalTimeUpdateHtLocation = glGetUniformLocation(g_computeUpdateHtProgram->Program , "u_totalTime"); g_processColumnFftLocation = glGetUniformLocation(g_computeFftProgram->Program, "u_processColumn"); g_stepsFftLocation = glGetUniformLocation(g_computeFftProgram->Program, "u_steps"); g_ModelLoc = glGetUniformLocation(g_program->Program, "u_Model"); g_ViewLoc = glGetUniformLocation(g_program->Program, "u_View"); g_ProjectionLoc = glGetUniformLocation(g_program->Program, "u_Projection"); g_normalMatrixLocation = glGetUniformLocation(g_program->Program, "u_normalMatrix"); g_lightDirectionLocation = glGetUniformLocation(g_program->Program, "u_lightDirection"); g_colorLocation = glGetUniformLocation(g_program->Program, "u_color"); g_vertexLocation = glGetAttribLocation(g_program->Program, "a_vertex"); g_texCoordLocation = glGetAttribLocation(g_program->Program, "a_texCoord"); // 建立一個方形的網格平面 CreateRectangularGridPlane(&gridPlane, LENGTH, LENGTH, N - 1, N - 1, GL_FALSE); //獲取該網格的索引總數 g_numberIndices = gridPlane.numberIndices; // 將當前網格以X軸為基礎旋轉90度使其處於X-Z平面 matrix = glm::rotate(matrix, glm::radians(-90.0f), glm::vec3(1.0f, 0.0f, 0.0f)); for (i = 0; i < gridPlane.numberVertices; i++) { gridPlane.vertices[i] = matrix * gridPlane.vertices[i]; } //儲存頂點座標的VBO glGenBuffers(1, &g_verticesVBO); glBindBuffer(GL_ARRAY_BUFFER, g_verticesVBO); glBufferData(GL_ARRAY_BUFFER, gridPlane.numberVertices * 4 * sizeof(GLfloat), (GLfloat*)gridPlane.vertices, GL_STATIC_DRAW); //儲存頂點紋理座標的VBO glGenBuffers(1, &g_texCoordsVBO); glBindBuffer(GL_ARRAY_BUFFER, g_texCoordsVBO); glBufferData(GL_ARRAY_BUFFER, gridPlane.numberVertices * 2 * sizeof(GLfloat), (GLfloat*)gridPlane.texCoords, GL_STATIC_DRAW); glBindBuffer(GL_ARRAY_BUFFER, 0); //儲存索引的VBO glGenBuffers(1, &g_indicesVBO); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_indicesVBO); glBufferData(GL_ELEMENT_ARRAY_BUFFER, gridPlane.numberIndices * sizeof(GLuint), (GLuint*)gridPlane.indices, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); ShapeDestroy(&gridPlane); //h0Data儲存波浪模型的初始值 h0Data = (GLfloat*)malloc(N * N * 2 * sizeof(GLfloat)); if (!h0Data) { return GL_FALSE; } //Phillips頻譜計算出初始波形 windDirection = glm::normalize(windDirection); for (i = 0; i < N; i++) { waveDirection[1] = ((GLfloat)i - (GLfloat)N / 2.0f) * (2.0f * GL_PI / LENGTH); for (k = 0; k < N; k++) { waveDirection[0] = ((GLfloat)k - (GLfloat)N / 2.0f) * (2.0f * GL_PI / LENGTH); phillipsSpectrumValue = PhillipsSpectrum(AMPLITUDE, LPWA, waveDirection, windDirection); h0Data[i * 2 * N + k * 2 + 0] = 1.0f / sqrtf(2.0f) * RandomNormal(0.0f, 1.0f) * phillipsSpectrumValue; h0Data[i * 2 * N + k * 2 + 1] = 1.0f / sqrtf(2.0f) * RandomNormal(0.0f, 1.0f) * phillipsSpectrumValue; } } //將資料儲存到一張貼圖當中，g_textureH0貼圖的R、G兩個通道分別儲存h0Data（相當於複數）的實部和虛部 glGenTextures(1, &g_textureH0); glBindTexture(GL_TEXTURE_2D, g_textureH0); glTexImage2D(GL_TEXTURE_2D, 0, GL_RG32F, N, N, 0, GL_RG, GL_FLOAT, h0Data); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); free(h0Data); //用於儲存波浪函式計算出來的複數值的貼圖 glGenTextures(1, &g_textureHt); glBindTexture(GL_TEXTURE_2D, g_textureHt); glTexImage2D(GL_TEXTURE_2D, 0, GL_RG32F, N, N, 0, GL_RG, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); //用於儲存頂點偏移值的貼圖（按行計算得到的值） glGenTextures(1, &g_textureDisplacement[0]); glBindTexture(GL_TEXTURE_2D, g_textureDisplacement[0]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RG32F, N, N, 0, GL_RG, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); //用於儲存頂點偏移值的貼圖（按列計算得到的值） glGenTextures(1, &g_textureDisplacement[1]); glBindTexture(GL_TEXTURE_2D, g_textureDisplacement[1]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RG32F, N, N, 0, GL_RG, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); //儲存法線向量值 glGenTextures(1, &g_textureNormal); glBindTexture(GL_TEXTURE_2D, g_textureNormal); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, N, N, 0, GL_RGBA, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glBindTexture(GL_TEXTURE_2D, 0); //生成逆傅立葉變換所需要的蝶形演算法使用的索引值 butterflyIndices = (GLint*)malloc(N * sizeof(GLint)); if (!butterflyIndices) { return GL_FALSE; } //使用GPU計算FFT需要先把第一次迭代的索引計算好例：N=8時 索引為(0,4) (1,5) (2,6) (3,7) butterflyIndicesAsFloat = (GLfloat*)malloc(N * sizeof(GLfloat)); if (!butterflyIndicesAsFloat) { free(butterflyIndices); return GL_FALSE; } for (i = 0; i < N; i++) { butterflyIndices[i] = i; } FourierButterflyShuffleFFTi(butterflyIndices, butterflyIndices, N); for (i = 0; i < N; i++) { butterflyIndicesAsFloat[i] = (GLfloat)butterflyIndices[i]; } free(butterflyIndices); //將計算好的索引值儲存到貼圖當中 glGenTextures(1, &g_textureIndices); glBindTexture(GL_TEXTURE_1D, g_textureIndices); glTexImage1D(GL_TEXTURE_1D, 0, GL_R32F, N, 0, GL_RED, GL_FLOAT, butterflyIndicesAsFloat); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glBindTexture(GL_TEXTURE_1D, 0); free(butterflyIndicesAsFloat); //將所需要的迭代次數傳遞到FFT的計算著色器中 glUseProgram(g_computeFftProgram->Program); glUniform1i(g_stepsFftLocation, steps); //設定渲染使用的VAO glUseProgram(g_program->Program); glGenVertexArrays(1, &g_vao); glBindVertexArray(g_vao); glBindBuffer(GL_ARRAY_BUFFER, g_verticesVBO); glVertexAttribPointer(g_vertexLocation, 4, GL_FLOAT, GL_FALSE, 0, 0); glEnableVertexAttribArray(g_vertexLocation); glBindBuffer(GL_ARRAY_BUFFER, g_texCoordsVBO); glVertexAttribPointer(g_texCoordLocation, 2, GL_FLOAT, GL_FALSE, 0, 0); glEnableVertexAttribArray(g_texCoordLocation); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_indicesVBO); glBindVertexArray(0); lightDirection = glm::normalize(lightDirection); GLfloat HelpLight[3]; HelpLight[0] = lightDirection.x; HelpLight[1] = lightDirection.y; HelpLight[2] = lightDirection.z; glUniform3fv(g_lightDirectionLocation, 1, HelpLight); GLfloat HelpColor[4]; HelpColor[0] = color.x; HelpColor[1] = color.y; HelpColor[2] = color.z; HelpColor[3] = color.w; glUniform4fv(g_colorLocation, 1, HelpColor); glUseProgram(0); glClearColor(0.0f, 0.0f, 0.0f, 0.0f); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); return GL_TRUE; } GLboolean OceanMeshForGPU::update(GLfloat time, glm::mat4 Model, glm::mat4 View, glm::mat4 Perspective, glm::vec3 CamPos, GLuint ReflectText) { static GLfloat totalTime = 0.0f; //將所需要的三大變換矩陣傳入到繪製用的著色器當中 glUseProgram(g_program->Program); glm::mat3 normalMatrix = glm::mat3(Model); glUniformMatrix4fv(g_ModelLoc, 1, GL_FALSE, glm::value_ptr(Model)); glUniformMatrix4fv(g_ViewLoc, 1, GL_FALSE, glm::value_ptr(View)); glUniformMatrix4fv(g_ProjectionLoc, 1, GL_FALSE, glm::value_ptr(Perspective)); glUniformMatrix3fv(g_normalMatrixLocation, 1, GL_FALSE, glm::value_ptr(normalMatrix)); glUniform3fv(glGetUniformLocation(g_program->Program, "camPos"), 1, &CamPos[0]); glUseProgram(0); //使用Update計算著色器並繫結初始值貼圖和即時值貼圖 glUseProgram(g_computeUpdateHtProgram->Program); glBindImageTexture(0, g_textureH0, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RG32F); glBindImageTexture(1, g_textureHt, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RG32F); //傳遞執行時間 glUniform1f(g_totalTimeUpdateHtLocation, totalTime); //建立一個N*N大小的工作組，即同時計算所有的頂點高度值 glDispatchCompute(N, N, 1); //確保所有的資料都寫入到貼圖裡了 glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT); //使用FFT計算著色器對結果進行逆變換 glUseProgram(g_computeFftProgram->Program); //繫結索引貼圖、上個計算著色器所得結果的波浪函式貼圖、將要儲存偏移值的貼圖 glBindImageTexture(0, g_textureHt, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RG32F); glBindImageTexture(1, g_textureDisplacement[0], 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RG32F); glBindImageTexture(2, g_textureIndices, 0, GL_FALSE, 0, GL_READ_ONLY, GL_R32F); glUniform1i(g_processColumnFftLocation, 0); // 先對每一行進行逆變換 glDispatchCompute(1, N, 1); glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT); glBindImageTexture(0, g_textureDisplacement[0], 0, GL_FALSE, 0, GL_READ_ONLY, GL_RG32F); glBindImageTexture(1, g_textureDisplacement[1], 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RG32F); glUniform1i(g_processColumnFftLocation, 1); // 再對每一列進行逆變換 glDispatchCompute(1, N, 1); glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT); //更新法線向量 glUseProgram(g_computeUpdateNormalProgram->Program); glBindImageTexture(0, g_textureDisplacement[1], 0, GL_FALSE, 0, GL_READ_ONLY, GL_RG32F); glBindImageTexture(1, g_textureNormal, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RGBA32F); glDispatchCompute(N, N, 1); glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT); glUseProgram(g_program->Program); glBindVertexArray(g_vao); //將波浪高度貼圖繫結在GL_TEXTURE0 glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, g_textureDisplacement[1]); //將法線貼圖繫結在GL_TEXTURE1 glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, g_textureNormal); glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, ReflectText); //根據索引開始繪製 glDrawElements(GL_TRIANGLES, g_numberIndices, GL_UNSIGNED_INT, 0); //重置GL_TEXTURE0 glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, 0); //重置GL_TEXTURE1 glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, 0); glBindVertexArray(0); totalTime += time; return GL_TRUE; }