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POCreate a triangle that continuously rotates around it’s y-axis in OpenGl
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  1. POCreate a triangle that continuously rotates around it’s y-axis in OpenGl
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    copied!<p>Im wondering how to rotate a OpenGL triangle around its Y-Axis in OpenGL, Ive been able to translate the triangle from object space to clip space. Im wondering if anyone has any experience with this issue and may be able to lend a hand.</p> <p>Main.cpp</p> <pre><code>#include &lt;iostream&gt; #include &lt;fstream&gt; #include &lt;sstream&gt; #include &lt;GL/glew.h&gt; #include &lt;GL/freeglut.h&gt; #include &lt;glm/glm.hpp&gt; #include &lt;glm/gtc/matrix_transform.hpp&gt; #include &lt;Windows.h&gt; using namespace std; using namespace glm; const int windowWidth = 1024; const int windowHeight = 768; GLuint VBO; const int NUMVERTS = 3; GLuint gModelToWorldTransformLocation; GLuint gWorldToViewTransformLocation; GLuint gProjectionTransformLocation; struct SimpleVertex { vec3 pos; vec4 colour; }; static void renderSceneCallBack() { static mat4 modelToWorldTransform = mat4(1.0f); static mat4 worldToViewTransform = lookAt( vec3(0.0f,0.0f,3.0f), // position of your camera, in world space vec3(0.0f,0.0f,0.0f), // look at in world space vec3(0.0f,1.0f,0.0f) // Camera up direction (set to 0,-1,0 to look upside-down) ); static mat4 projectionTransform = perspective(45.0f, (float)windowWidth / (float)windowHeight, 1.0f, 100.0f); glUniformMatrix4fv(gModelToWorldTransformLocation, 1, GL_FALSE, &amp;modelToWorldTransform[0][0]); glUniformMatrix4fv(gWorldToViewTransformLocation, 1, GL_FALSE, &amp;worldToViewTransform[0][0]); glUniformMatrix4fv(gProjectionTransformLocation, 1, GL_FALSE, &amp;projectionTransform[0][0]); glClear(GL_COLOR_BUFFER_BIT); glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); glBindBuffer(GL_ARRAY_BUFFER, VBO); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(SimpleVertex), 0); glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(SimpleVertex), (const GLvoid*)12); glDrawArrays(GL_TRIANGLES, 0, NUMVERTS); glDisableVertexAttribArray(0); glDisableVertexAttribArray(1); glutSwapBuffers(); } static void initializeGlutCallbacks() { glutDisplayFunc(renderSceneCallBack); glutIdleFunc(renderSceneCallBack); } static void createVertexBuffer() { // Create some vertices to put in our VBO. // Create vertex buffer SimpleVertex vertices[] = { {vec3(-0.5f, -0.5f, 0.0f), vec4(1.0f, 0.0f, 0.0f, 1.0f)}, {vec3(0.5f, -0.5f, 0.0f), vec4(0.0f, 1.0f, 0.0f, 1.0f)}, {vec3( 0.0f, 0.5f, 0.0f), vec4(0.0f, 0.0f, 1.0f, 1.0f)} }; glGenBuffers(1, &amp;VBO); glBindBuffer(GL_ARRAY_BUFFER, VBO); glBufferData(GL_ARRAY_BUFFER, sizeof(SimpleVertex) * 3, vertices, GL_STATIC_DRAW); } static void addShader(GLuint shaderProgram, const char* pShaderText, GLenum shaderType) { GLuint shaderObj = glCreateShader(shaderType); if (shaderObj == 0) { cerr&lt;&lt;"Error creating shader type "&lt;&lt;shaderType&lt;&lt;endl; exit(0); } const GLchar* p[1]; p[0] = pShaderText; GLint Lengths[1]; Lengths[0]= strlen(pShaderText); glShaderSource(shaderObj, 1, p, Lengths); glCompileShader(shaderObj); GLint success; glGetShaderiv(shaderObj, GL_COMPILE_STATUS, &amp;success); if (!success) { GLchar InfoLog[1024]; glGetShaderInfoLog(shaderObj, 1024, NULL, InfoLog); cerr&lt;&lt;"Error compiling shader type "&lt;&lt;shaderType&lt;&lt;": "&lt;&lt;InfoLog&lt;&lt;endl; exit(1); } glAttachShader(shaderProgram, shaderObj); } const string readFileToString(char* filename) { ifstream file (filename, ios::in); if (file.is_open()) { stringstream continut; continut &lt;&lt; file.rdbuf(); continut &lt;&lt; '\0'; return continut.str(); } return ""; } static void buildShaders() { GLuint shaderProgram = glCreateProgram(); if (shaderProgram == 0) { cerr&lt;&lt;"Error creating shader program\n"; exit(1); } string VS = readFileToString("vertexShader.glsl"); string FS = readFileToString("fragmentShader.glsl"); addShader(shaderProgram, VS.c_str(), GL_VERTEX_SHADER); addShader(shaderProgram, FS.c_str(), GL_FRAGMENT_SHADER); GLint success = 0; GLchar errorLog[1024] = { 0 }; glLinkProgram(shaderProgram); glGetProgramiv(shaderProgram, GL_LINK_STATUS, &amp;success); if (success == 0) { glGetProgramInfoLog(shaderProgram, sizeof(errorLog), NULL, errorLog); cerr&lt;&lt;"Error linking shader program: "&lt;&lt;errorLog&lt;&lt;endl; exit(1); } glValidateProgram(shaderProgram); glGetProgramiv(shaderProgram, GL_VALIDATE_STATUS, &amp;success); if (!success) { glGetProgramInfoLog(shaderProgram, sizeof(errorLog), NULL, errorLog); cerr&lt;&lt;"Error linking shader program: "&lt;&lt;errorLog&lt;&lt;endl; exit(1); } glUseProgram(shaderProgram); gModelToWorldTransformLocation = glGetUniformLocation(shaderProgram, "gModelToWorldTransform"); //assert(gModelToWorldTransformLocation != 0xFFFFFFFF); gWorldToViewTransformLocation = glGetUniformLocation(shaderProgram, "gWorldToViewTransform"); //assert(gWorldToViewTransformLocation != 0xFFFFFFFF); gProjectionTransformLocation = glGetUniformLocation(shaderProgram, "gProjectionTransform"); //assert(gProjectionTransformLocation != 0xFFFFFFFF); } int main(int argc, char** argv) { glutInit(&amp;argc, argv); glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA); glutInitWindowSize(windowWidth, windowHeight); glutInitWindowPosition(100, 100); glutCreateWindow("Transformations"); initializeGlutCallbacks(); // Must be done after glut is initialized! GLenum res = glewInit(); if (res != GLEW_OK) { cerr&lt;&lt;"Error: "&lt;&lt;glewGetErrorString(res)&lt;&lt;"\n"; return 1; } buildShaders(); glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Create a vertex buffer createVertexBuffer(); glutMainLoop(); return 0; } </code></pre> <p>VertexShader</p> <pre><code>#version 330 layout (location = 0) in vec3 Position; layout (location = 1) in vec4 Colour; out vec4 Colour0; uniform mat4 gModelToWorldTransform; uniform mat4 gWorldToViewTransform; uniform mat4 gProjectionTransform; void main() { vec4 vertexPositionInModelSpace = vec4(Position, 1); vec4 vertexInWorldSpace = gModelToWorldTransform * vertexPositionInModelSpace; vec4 vertexInViewSpace = gWorldToViewTransform * vertexInWorldSpace; vec4 vertexInHomogeneousClipSpace = gProjectionTransform * vertexInViewSpace; gl_Position = vertexInHomogeneousClipSpace; Colour0 = Colour; } </code></pre> <p>FragmentShader</p> <pre><code>#version 330 in vec4 Colour0; out vec4 FragColor; void main() { FragColor = Colour0; } </code></pre>
 

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