How can I use multiple shader in my renderer? - c++

Question

I am trying to make my renderer able to use either default or custom shader.
class Renderer
{
public:
void Create()
{
//Setup vao, vbo, ebo, quad indices, add data to ebo,
//create default Shader
//set camera projection
}
void Map()
{
vertexData = (VertexData*)glMapBufferRange(...);
}
void Draw(Rectangle destRect, Rectangle texCoordRect, Texture* texture)
{
//4 times for 4 different corners
float textureSlot = FindTexture(texture);
AddDataToMappedBuffer(position, texCoords, textureSlot, color);
indexCount += 6;
}
void Unmap()
{
glUnmapBuffer(...);
}
void Render()
{
Unmap();
shader.UniformMatrix4fv("projection", camera.getProjection());
for(uint i = 0; i < texture.size(); ++i)
{
texture[i]->Bind(i);
}
BindVAO();
DrawElements(TRIANGELS, indexCount, UNSIGNED_INT, nullptr);
UnbindVAO();
For(uint i = 0; i < texture.size(); ++i)
{
texture[i]->Unbind(i);
}
indexCount = 0;
texture.clear();
}
float Renderer2D::FindTexture(Texture* t)
{
float result = 0.0f;
bool found = false;
for (uint i = 0; i < texture.size(); ++i) {
if (texture[i] == t) {
result = static_cast<float>(i + 1);
found = true;
break;
}
}
if (!found) {
if (texture.size() >= MAX_TEXTURES) {
Render();
Map();
}
texture.push_back(t);
result = static_cast<float>(texture.size());
}
return result;
}
private:
std::vector<Texture*> texture;
uint vao, vbo, ebo;
VertexData* vertexData;
float FindTexture(Texture*);
Shader shader;
Camera2D camera;
};
int main()
{
Renderer renderer;
renderer.Create();
while(!quit)
{
//Clear color etc.
renderer.Map();
renderer.Draw(Rectangle(0.0f, 0.0f, 500.0f, 500.0f), Rectangle(0.0f, 0.0f, 1.0f, 1.0f), texture("sometexture.png"));
renderer.Render();
}
}
that is how it works right now.
I would like my renderer to be like this:
in Draw method set shader
check if this shader is in an array
if it is, do not do another draw call - use shader which is already in an array
if it is not, add this shader to an array, use it and do another draw call
I tried to do method which find shader - similar to texture - and go through all shaders and use them. It do not do exactly what I want.
std::vector<Shader*> shader;
void Renderer2D::FindShader(Shader* sh)
{
bool found = false;
for (uint i = 0; i < shader.size(); ++i) {
if (shader[i] == sh) {
found = true;
return;
}
}
if (!found) {
shader.push_back(sh);
Render();
Map();
}
}
void Render()
{
Unmap();
for(const auto& shader : shader)
{
shader->UseProgram();
shader.UniformMatrix4fv("projection", camera.getProjection());
}
for(uint i = 0; i < texture.size(); ++i)
{
texture[i]->Bind(i);
}
BindVAO();
DrawElements(TRIANGELS, indexCount, UNSIGNED_INT, nullptr);
UnbindVAO();
For(uint i = 0; i < texture.size(); ++i)
{
texture[i]->Unbind(i);
}
indexCount = 0;
texture.clear();
}
void Draw(Rectangle destRect, Rectangle texCoordRect, Texture* texture, Shader* shader)
{
FindShader(shader);
float textureSlot = FindTexture(texture);
AddDataToMappedBuffer(position, texCoords, textureSlot, color);
indexCount += 6;
}
I have also tried to find shader without doing another draw call when shader is not found - only add it to an array - and in render method loop through all shaders and do draw call. It also did not work well.
How should I do it?