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POCube is not rendering in OpenGL
 

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  1. POCube is not rendering in OpenGL
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    <p>I'm trying to write a basic OpenGL 3.3 program with shaders, buffers, etc. drawing a cube. The problem is that the cube is not drawn. Sorry for such an amout of code, but i feel like the error might be anywhere, because to me it all seems right: display function is looping, shaders are compiled, matrices are passed to shaders. I suspecting that something might be wrong with culling. Please take a look. Here is the code (I'm using freeglut, first init() is called, then display runs in a loop):</p> <p>initialization code:</p> <pre><code>struct ProgramData { GLuint theProgram; GLuint iModel; GLuint iView; GLuint iProjection; }; ProgramData shaderProgram; ProgramData LoadProgram(const std::string &amp;strVertexShader, const std::string &amp;strFragmentShader) { std::vector&lt;GLuint&gt; shaderList; shaderList.push_back(LoadShader(GL_VERTEX_SHADER, strVertexShader)); shaderList.push_back(LoadShader(GL_FRAGMENT_SHADER, strFragmentShader)); ProgramData data; data.theProgram = CreateProgram(shaderList); data.iModel = glGetUniformLocation(data.theProgram, "mModel"); data.iView = glGetUniformLocation(data.theProgram, "mView"); data.iProjection = glGetUniformLocation(data.theProgram, "mProjection"); return data; } float cube_vertices[] = { -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, -1.0f, GREEN_COLOR, BLUE_COLOR, RED_COLOR, BROWN_COLOR, GREEN_COLOR, BLUE_COLOR, RED_COLOR, BROWN_COLOR, }; GLubyte cube_elements[] = { 0,1,2, 2,3,0, 0,3,4, 4,5,0, 0,5,6, 6,1,0, 1,6,7, 7,2,1, 7,4,3, 3,2,7, 4,7,6, 6,5,4 }; void InitializeProgram() { //initialize vertex buffer glGenBuffers(1, &amp;vertex_buffer_obj); glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_obj); glBufferData(GL_ARRAY_BUFFER, sizeof(cube_vertices), cube_vertices, GL_STATIC_DRAW); glBindBuffer(GL_ARRAY_BUFFER, 0); //initialize index buffer glGenBuffers(1, &amp;index_buffer_obj); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_obj); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(cube_elements), cube_elements, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); shaderProgram = LoadProgram("shader.vert", "shader.frag"); } void init() { InitializeProgram(); int numberOfVertices = 8; size_t color_data_offset = sizeof(float) * 3 * numberOfVertices; glGenVertexArrays(1, &amp;vao); glBindVertexArray(vao); glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_obj); glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0); glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, (void*)color_data_offset); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_obj); glBindVertexArray(0); glEnable(GL_CULL_FACE); glCullFace(GL_BACK); glFrontFace(GL_CW); glEnable(GL_DEPTH_TEST); glDepthMask(GL_TRUE); glDepthFunc(GL_LEQUAL); glDepthRange(0.0f, 1.0f); } </code></pre> <p>vertex shader:</p> <pre><code>#version 330 layout (location = 0) in vec3 inPosition; layout (location = 1) in vec3 color; uniform mat4 mProjection; uniform mat4 mView; uniform mat4 mModel; smooth out vec3 theColor; void main() { gl_Position = mProjection * mView * mModel * vec4(inPosition, 1); theColor = color; } </code></pre> <p>fragment shader:</p> <pre><code>#version 330 smooth in vec3 theColor; out vec4 outputColor; void main() { outputColor = vec4(theColor, 1); } </code></pre> <p>draw code:</p> <pre><code>glm::vec3 cam_pos(3, 2, 3); void display() { glClearColor(0.3f, 0.3f, 0.3f, 1.0f); glClearDepth(1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glUseProgram(shaderProgram.theProgram); glm::mat4 model_matrix = glm::translate(glm::vec3(0, 0, 0)); glm::mat4 view_matrix = glm::lookAt(cam_pos, glm::vec3(0, 0, 0), glm::vec3(0, 0, 1)); glm::mat4 proj_matrix = glm::perspective(45.0f, 1.0f, 1.0f, 100.0f); glUniformMatrix4fv(shaderProgram.iProjection, 1, GL_FALSE, glm::value_ptr(proj_matrix)); glUniformMatrix4fv(shaderProgram.iView, 1, GL_FALSE, glm::value_ptr(view_matrix)); glUniformMatrix4fv(shaderProgram.iModel, 1, GL_FALSE, glm::value_ptr(model_matrix)); glBindVertexArray(vao); int size; glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &amp;size); glDrawElements(GL_TRIANGLES, size / sizeof(GLubyte), GL_UNSIGNED_SHORT, 0); glBindVertexArray(0); glUseProgram(0); glutSwapBuffers(); glutPostRedisplay(); } </code></pre> <p>UPD: in init method when an offset for colors is calculated should be <code>sizeof(float) * 3 * numberOfVertices</code> instead of <code>sizeof(GLubyte) * 3 * numberOfVertices</code>, colors are stored as floats. Rendering problem not solved.</p> <p>SOLVED: thank you for help. See my answer below.</p>
    singulars
    1. PO
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      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USMaksim Borisov
    1. USMaksim Borisov
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
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      1. PTAnswer
    2. PO
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      1. PTAnswer
    1. VO
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      1. POCube is not rendering in OpenGL
      1. This table or related slice is empty.
      1. VTDownMod
    2. VO
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      1. POCube is not rendering in OpenGL
      1. This table or related slice is empty.
      1. VTUpMod
    1. COAre you using a right handed system for your model space?
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      1. POCube is not rendering in OpenGL
      1. USlegends2k
    2. COI think yes, it's right handed
      singulars
      1. POCube is not rendering in OpenGL
      1. USMaksim Borisov
    3. COThen shouldn't the front face be CCW?
      singulars
      1. POCube is not rendering in OpenGL
      1. USlegends2k
 

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