ultimatepp/bazaar/GLPainter/Image.cpp

#include "GLPainter.h"

namespace Upp {

void GLBind(const Image& img, dword style)
{
	glBindTexture(GL_TEXTURE_2D, GetTextureForImage(style, img));
}

Sizef GLMakeViewScale(Size view_size)
{
	return Sizef(2.0 / view_size.cx, -2.0 / view_size.cy);
}

const GLMesh& GLRectMesh()
{
	static GLMesh mesh;
	ONCELOCK {
		static const float box[] = {
			0, 0, // 0
			0, 1, // 1
			1, 0, // 2
			1, 1, // 3
		};
		static const int ndx[] = {
			0, 1, 2, 1, 2, 3
		};
		mesh.Add(box, 2, 4).Index(ndx, 6);
	}
	return mesh;
}

void GLDrawImage(Sizef vs, const Rect& rect, const Image& img, double alpha)
{
	static GLCode program(R"(
		#version 330 core
		uniform vec2 offset;
		uniform vec2 scale;
	    in      vec2 aPos;
		out vec2 tPos;
	    void main()
	    {
			gl_Position = vec4(scale * aPos + offset, 0, 1);
			tPos = aPos;
	    }
	)", R"(
		#version 330 core
		in vec2 tPos;
		uniform float alpha;
		uniform sampler2D s_texture;
		void main()
		{
		   gl_FragColor = alpha * texture2D(s_texture, tPos);
		}
	)");

	static int offset = program["offset"];
	static int scale = program["scale"];
	static int ialpha = program["alpha"];

	glEnable(GL_BLEND);
	glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

	GLBind(img);
	GLRectMesh().Draw(
		program(offset, vs * rect.TopLeft() + Sizef(-1, 1))
		       (scale, vs * rect.GetSize())
		       (ialpha, alpha)
	);
}

};