OpenGL multi-version cubemap shadow texture creation for point lights

gistfile1.txt

bool change_shadow_size (int dims) {
	game_log ("generating shadow textures, size %i", dims);
	g_sett.shadow_size = dims;
	glBindFramebuffer(GL_FRAMEBUFFER, g_shads.cube_fb);
	{ // colour cube texture
		bind_cube_texture (0, g_shads.cube_colour_tex);
		for (int i = 0; i < 6; i++) {
			// NOTE: 16F and FLOAT are NOT part of GL 2.1 but MESA didn't support
			// the 16 and INT which ARE part of GL 2.1
			glTexImage2D (GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGBA16F,
				g_sett.shadow_size, g_sett.shadow_size, 0, GL_RED, GL_FLOAT, NULL);
		}
		glTexParameteri (GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexParameteri (GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri (GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
		glTexParameteri (GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		glTexParameteri (GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		glFramebufferTexture2D (GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
			GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, g_shads.cube_colour_tex, 0);
		bind_cube_texture (0, 0);
	}
	{ // create renderbuffer
		glBindRenderbuffer (GL_RENDERBUFFER, g_shads.render_buffer);
		glRenderbufferStorage (GL_RENDERBUFFER, GL_DEPTH_COMPONENT,
			g_sett.shadow_size, g_sett.shadow_size);
		// attach renderbuffer to framebuffer
		glFramebufferRenderbuffer (GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
			GL_RENDERBUFFER, g_shads.render_buffer);
	}
	if (!verify_bound_framebuffer ()) {
		game_log_err ("ERROR: verifying framebuffer for depth\n");
		return false;
	}
	glBindFramebuffer (GL_FRAMEBUFFER, 0);
	return true;
}