I've been working on a small project of my own for some time now, and have started the process of drawing things to the screen. I've set up an OpenGL 3 environment with Allegro 5.2.1.1. All that is working about as expected.
The problem lies with my transformations. For some unknown reason, I seem to be unable to translate my objects individually. They all render with the exact same transformation, and I just can't figure out why this is happening.
For my test scene, I've made three simple structures and attempted to render them using three different transformations. This was the result:
http://imgur.com/a/ebLnw
The result I want, is this:
http://imgur.com/a/SvbEf
The code I used to render this scene is the following:
#SelectExpand
1 auto helper = hen::Core::getRenderHelper();
2
3 if (m_program != nullptr)
4 m_program->bind();
5
6 helper->setProjection(45.0f, 0.1f, 1000.0f);
7 helper->setView(m_pos, glm::vec3{}, glm::vec3{ 0.0f, 0.0f, 1.0f });
8
9 for (const auto& chunk : m_chunks)
10 {
11 helper->pushMatrix(glm::translate(glm::mat4{ 1.0f }, glm::vec3{ Chunk::SIZE * chunk.second->getPosition() }));
12 chunk.second->render();
13 helper->popMatrix();
14 }
The chunk render() method only renders the VBO associated with said chunk, which is the following:
#SelectExpand
5void hen::render::VBOBase::render() const
6{
7 glBindBuffer(GL_ARRAY_BUFFER, m_vertexBuffer);
8 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_indiceBuffer);
9
10 for (const auto& attribute : m_attributes)
11 {
12 glEnableVertexAttribArray(attribute.m_index);
13 glVertexAttribPointer(attribute.m_index, attribute.m_count, attribute.m_format, GL_FALSE, m_vertexSize, (const GLvoid*)attribute.m_offset);
14 }
15
16 glDrawElements(m_renderMode, m_indiceCount, GL_UNSIGNED_INT, (void*)0);
17
18 for (const auto& attribute : m_attributes)
19 glDisableVertexAttribArray(attribute.m_index);
20
21 glBindBuffer(GL_ARRAY_BUFFER, 0);
22 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
23}
Oddly enough, the desired result was obtained, albeit flickering, if I added an al_flip_display() inside the loop. It seems that only the first series of transformations pushed in with pushMatrix counts when flipping the display. Even weirder, any transformations applied, apply to all objects as long as they aren't popped before rendering the first object. Once one object has been drawn, any subsequent transformations are ignored. This really doesn't make any sense...
The push/popMatrix methods are as following:
#SelectExpand
2void hen::render::RenderHelper::pushMatrix(const glm::mat4& matrix)
3{
4 if (m_matrices.size() == 0)
5 m_matrices.push(matrix);
6 else
7 m_matrices.push(m_matrices.top() * matrix);
8
9 auto block = Core::getUniformBlockManager()->get("Matrix");
10 if (block != nullptr)
11 block->set<glm::mat4>("model", m_matrices.top());
12}
13void hen::render::RenderHelper::popMatrix()
14{
15 if (m_matrices.size() != 0)
16 m_matrices.pop();
17
18 auto block = Core::getUniformBlockManager()->get("Matrix");
19 if (block != nullptr)
20 block->set<glm::mat4>("model", m_matrices.size() == 0 ? glm::mat4{ 1.0f } : m_matrices.top());
21}
The RenderHelper::setView and setProjection methods sends the data to the GPU in the same manner as push/popMatrix, using uniform blocks.
Creating and updating the uniform block:
#SelectExpand
4 glGenBuffers(1, &m_handle);
5 ...
6 glBindBuffer(GL_UNIFORM_BUFFER, m_handle);
7 glBufferData(GL_UNIFORM_BUFFER, m_size, nullptr, GL_STATIC_DRAW);
8 glBindBuffer(GL_UNIFORM_BUFFER, 0);
9
10
11template<typename T>
12bool hen::render::UniformBlock::set(const std::string& name, const T& value) const
13{
14 ...
15 glBindBuffer(GL_UNIFORM_BUFFER, m_handle);
16 glBufferSubData(GL_UNIFORM_BUFFER, getOffset(name), sizeof(T), (GLvoid*)&value[0]);
17 glBindBuffer(GL_UNIFORM_BUFFER, 0);
18 return true;
19}
My vertex and fragment shader are as following:
#SelectExpand
3Vertex shader:
4#version 330 core
5
6layout (std140) uniform Matrix
7{
8 mat4 projection;
9 mat4 view;
10 mat4 model;
11} matrices;
12
13layout(location = 0) in vec3 inPosition;
14layout(location = 1) in vec3 inNormal;
15layout(location = 2) in vec2 inUV;
16layout(location = 3) in vec4 inColor;
17
18out VertexData
19{
20 vec3 normal;
21 vec2 uv;
22 vec4 color;
23} vertex;
24
25void main()
26{
27 gl_Position = matrices.projection * matrices.view * matrices.model * vec4(inPosition, 1);
28
29 vertex.normal = (matrices.model * vec4(inNormal, 0)).xyz;
30 vertex.uv = inUV;
31 vertex.color = inColor;
32}
33
34Fragment shader:
35#version 330 core
36
37in VertexData
38{
39 vec3 normal;
40 vec2 uv;
41 vec4 color;
42} vertex;
43
44out vec4 fragment;
45
46void main()
47{
48 fragment = vec4(vertex.color.xyz, 1.0);
49}
I know that my shaders are working, and the transformations are working to some degree. I'm able to rotate/scale/translate all the objects in bulk with constant transformations, even apply multiple transformations in a row.
I've stared at this issue for quite some time now, and I just can't figure out how to fix this, can't even figure out what is going on here... :/
Any help would be highly appreciated!
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