blender-archive/source/blender/gpu/shaders/gpu_shader_keyframe_diamond_frag.glsl

flat in vec4 radii;
flat in vec4 thresholds;

flat in vec4 finalColor;
flat in vec4 finalOutlineColor;

flat in int finalFlags;

out vec4 fragColor;

const float diagonal_scale = sqrt(0.5);

const float minmax_bias = 0.7;
const float minmax_scale = sqrt(1.0 / (1.0 + 1.0/minmax_bias));

bool test(int bit) {
	return (finalFlags & bit) != 0;
}

void main() {
	vec2 pos = gl_PointCoord - vec2(0.5);
	vec2 absPos = abs(pos);
	float radius = (absPos.x + absPos.y) * diagonal_scale;

	float outline_dist = -1.0;

	/* Diamond outline */
	if (test(0x1)) {
		outline_dist = max(outline_dist, radius - radii[0]);
	}

	/* Circle outline */
	if (test(0x2)) {
		radius = length(absPos);

		outline_dist = max(outline_dist, radius - radii[1]);
	}

	/* Top & Bottom clamp */
	if (test(0x4)) {
		outline_dist = max(outline_dist, absPos.y - radii[2]);
	}

	/* Left & Right clamp */
	if (test(0x8)) {
		outline_dist = max(outline_dist, absPos.x - radii[2]);
	}

	float alpha = 1 - smoothstep(thresholds[0], thresholds[1], abs(outline_dist));

	/* Inside the outline. */
	if (outline_dist < 0) {
		/* Middle dot */
		if (test(0x10)) {
			alpha = max(alpha, 1 - smoothstep(thresholds[2], thresholds[3], radius));
		}

		/* Up and down arrow-like shading. */
		if (test(0x300)) {
			float ypos = -1.0;

			/* Up arrow (maximum) */
			if (test(0x100)) {
				ypos = max(ypos, pos.y);
			}
			/* Down arrow (minimum) */
			if (test(0x200)) {
				ypos = max(ypos, -pos.y);
			}

			/* Arrow shape threshold. */
			float minmax_dist = (ypos - radii[3]) - absPos.x * minmax_bias;
			float minmax_step = smoothstep(thresholds[0], thresholds[1], minmax_dist * minmax_scale);

			/* Reduced alpha for uncertain extremes. */
			float minmax_alpha = test(0x400) ? 0.55 : 0.85;

			alpha = max(alpha, minmax_step * minmax_alpha);
		}

		fragColor = mix(finalColor, finalOutlineColor, alpha);
	}
	/* Outside the outline. */
	else {
		fragColor = vec4(finalOutlineColor.rgb, finalOutlineColor.a * alpha);
	}
}