59 lines
2.3 KiB
GLSL
59 lines
2.3 KiB
GLSL
layout (location = 0) in vec2 a_pos;
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out vec2 v_uv;
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out vec2 v_world;
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out vec2 v_particle_velocity;
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out float v_particle_valid;
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layout (std140) uniform ParticleGpuValidationUBO {
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highp vec4 u_pass;
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highp vec4 u_marker;
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highp vec4 u_mask;
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highp vec4 u_visual;
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highp mat4 u_matrix;
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};
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uniform sampler2D u_state_texture;
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uniform sampler2D u_field_texture;
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uniform sampler2D u_next_field_texture;
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void main() {
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v_uv = a_pos;
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v_world = a_pos;
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v_particle_velocity = vec2(0.0);
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v_particle_valid = 1.0;
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if (u_pass.x < 1.5) {
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gl_Position = vec4(a_pos * 2.0 - 1.0, 0.0, 1.0);
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} else if (u_pass.x > 3.5) {
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// 40-05: a_pos.x packs State texel X plus a static line endpoint.
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// State position, interpolated Field velocity, speed color and streak
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// orientation are all evaluated on GPU; the CPU never supplies live
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// particle position, direction, or color data.
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float endpoint = mod(a_pos.x, 2.0) * 2.0 - 1.0;
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vec2 stateIndex = vec2(floor(a_pos.x * 0.5), a_pos.y);
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vec2 stateUV = (stateIndex + vec2(0.5)) / u_mask.xy;
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vec2 position = texture(u_state_texture, stateUV).rg;
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vec4 field0 = texture(u_field_texture, position);
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vec4 field1 = texture(u_next_field_texture, position);
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vec2 velocity = mix(field0.rg * 2.0 - 1.0, field1.rg * 2.0 - 1.0, u_marker.x);
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bool valid = field0.a >= 0.5 && field1.a >= 0.5 && !any(isnan(velocity));
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vec2 mercatorVelocity = vec2(velocity.x, -velocity.y);
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float speed = length(mercatorVelocity);
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v_uv = position;
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v_world = position;
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v_particle_velocity = mercatorVelocity;
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v_particle_valid = valid && speed > 0.00001 ? 1.0 : 0.0;
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if (v_particle_valid < 0.5) {
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gl_Position = vec4(-2.0, -2.0, 0.0, 1.0);
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} else {
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vec2 direction = mercatorVelocity / speed;
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vec2 streakPosition = position + direction * endpoint * u_visual.y * 0.5;
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gl_Position = vec4(streakPosition * 2.0 - 1.0, 0.0, 1.0);
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}
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} else {
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// VALIDATION ONLY: a_pos is canonical z0 world geometry; u_matrix is
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// PaintParameters::matrixForTile() for the selected MapLibre world copy.
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gl_Position = u_matrix * vec4(a_pos * 8192.0, 0.0, 1.0);
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}
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}
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