render.cc

void Render_DrawTile(f64 X, f64 Y, f64 Width, f64 Height, i32 map_width, i32 map_height, i32 TileX, i32 TileY, OpenglImage image) {
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	GLuint TextureID = image.id;
	GLint ProgramID = tile_draw_shader.id;
	// NOTE: ceil prevents pixel gaps when tile edges are exactly aligned agaisnt one another
	// doesnt always happen but will see an ocassional "shimmer" of one if there is no ceil
	f64 TileScaleX = 1.0 / (f64)image.width * (f64)map_width;
	f64 TileScaleY = 1.0 / (f64)image.height * (f64)map_height;
	f64 SizeX = ceil(Width * meters_to_pixels);
	f64 SizeY = ceil(Height * meters_to_pixels);
	f64 PositionX = ceil(world_render_position.x + (X * meters_to_pixels) - SizeX * 0.5);
	f64 PositionY = ceil(world_render_position.y + (Y * meters_to_pixels) - SizeY * 0.5);

	glUseProgram(ProgramID);

	glEnableVertexAttribArray(0);
	glEnableVertexAttribArray(1);

	glBindBuffer(GL_ARRAY_BUFFER, rectangle_vertex_buffer_object);
	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(f32), (void *)0);
	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(f32), (void *)(2 * sizeof(f32)));

	GLint InputTextureUniform = glGetUniformLocation(ProgramID, "Texture");
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, TextureID);
	glUniform1i(InputTextureUniform, GL_TEXTURE0);

	GLint TileScaleUniform = glGetUniformLocation(ProgramID, "TileScale");
	glUniform2f(TileScaleUniform, (GLfloat)TileScaleX, (GLfloat)TileScaleY);

	GLint TilePositionUniform = glGetUniformLocation(ProgramID, "TilePosition");
	glUniform2f(TilePositionUniform, (GLfloat)(TileScaleX * (GLfloat)TileX), (GLfloat)(TileScaleY * (GLfloat)TileY));

	GLint PositionUniform = glGetUniformLocation(ProgramID, "Position");
	glUniform2f(PositionUniform, (GLfloat)PositionX, (GLfloat)PositionY);

	GLint SizeUniform = glGetUniformLocation(ProgramID, "Size");
	glUniform2f(SizeUniform, (GLfloat)SizeX, (GLfloat)SizeY);

	GLint AmbientLightUniform = glGetUniformLocation(ProgramID, "AmbientLight");
	glUniform3fv(AmbientLightUniform, 1, ambient_light);

	GLint TestLightPositionUniform = glGetUniformLocation(ProgramID, "TestLightPosition");
	//glUniform2f(TestLightPositionUniform, (GLfloat)(800.0 + 800.0 * sin(time.elapsed_time * 0.1)), (GLfloat)(window_resolution.h * 0.5));
	glUniform2f(TestLightPositionUniform, 0.0f, 0.0f);

	GLint TestLightBottomUniform = glGetUniformLocation(ProgramID, "light_test_bottom");
	glUniform1f(TestLightBottomUniform, light_test_bottom);

	GLint TestLightTopUniform = glGetUniformLocation(ProgramID, "light_test_top");
	glUniform1f(TestLightTopUniform, light_test_top);

	GLint MVPUniform = glGetUniformLocation(ProgramID, "MVP");
	glUniformMatrix4fv(MVPUniform, 1, GL_FALSE, glm::value_ptr(mvp_matrix));

	glDrawArrays(GL_TRIANGLES, 0, 6);

	glDisableVertexAttribArray(0);
	glDisableVertexAttribArray(1);
}