project-swan/libcygnet/include/cygnet/RenderQueue.h

#pragma once

#include <vector>

#include "GlWrappers.h"

namespace Cygnet {

class RenderQueue {
public:
	struct Locs {
		GLint transform;
		GLint position;
		GLint texCoord;
		GLint tex;
	};

	RenderQueue(Locs locs, float scale):
			locs_(std::move(locs)), pixScale_(scale) {};
	RenderQueue(GlProgram &prog, float scale):
		RenderQueue({
			prog.uniformLoc("transform"),
			prog.attribLoc("position"),
			prog.attribLoc("texCoord"),
			prog.uniformLoc("tex"),
		}, scale) {}

	void show(GlTexture &tex, float x, float y) {
		show(tex.id(), x, y, 1, 1, tex.width(), tex.height());
	}
	void show(GlTexture &tex, float x, float y, float sx, float sy) {
		show(tex.id(), x, y, sx, sy, tex.width(), tex.height());
	}
	void show(GlTexture &tex, float x, float y, float sx, float sy, float w, float h) {
		show(tex.id(), x, y, sx, sy, w, h);
	}
	void show(GLuint tex, float x, float y, float sx, float sy, float w, float h) {
		queue_.push_back({ tex, x, y, sx, sy, w * pixScale_, h * pixScale_ });
	}

	float getScaleX() { return mat_[0]; }
	float getScaleY() { return -mat_[4]; }
	float getTranslateX() { return mat_[3]; }
	float getTranslateY() { return mat_[5]; }
	void setScale(float sx, float sy) { mat_[0] = sx; mat_[4] = -sy; }
	void setTranslate(float tx, float ty) { mat_[2] = tx; mat_[5] = ty; }

	void draw();

private:
	struct Entry {
		GLuint tex;
		float x, y;
		float sx, sy;
		float w, h;
	};

	Locs locs_;
	float pixScale_;
	GLfloat mat_[9] = {
		1,  0, 0,  // scaleX, 0,       translateX,
		0, -1, 0,  // 0,      -scaleY, translateY,
		0,  0, 1,  // 0,      0,       1
	};

	std::vector<Entry> queue_;
};

}