Fix y billboard shear when rotating camera

Fixes shear effect with `BILLBOARD_FIXED_Y` when the camera is rotated around the z-axis by rotating the mesh correctly into view space.

Also removes shearing effects that occur when rotating the mesh by excluding the model rotation and scale from the billboard matrix.

(cherry picked from commit d3850a0954)
This commit is contained in:
John Wigg 2021-08-27 12:30:29 +01:00 committed by Rémi Verschelde
parent 168292fa00
commit d484e30247
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@ -647,12 +647,10 @@ void SpatialMaterial::_update_shader() {
}
} break;
case BILLBOARD_FIXED_Y: {
code += "\tMODELVIEW_MATRIX = INV_CAMERA_MATRIX * mat4(CAMERA_MATRIX[0],WORLD_MATRIX[1],vec4(normalize(cross(CAMERA_MATRIX[0].xyz,WORLD_MATRIX[1].xyz)), 0.0),WORLD_MATRIX[3]);\n";
code += "\tMODELVIEW_MATRIX = INV_CAMERA_MATRIX * mat4(vec4(normalize(cross(vec3(0.0, 1.0, 0.0), CAMERA_MATRIX[2].xyz)),0.0),vec4(0.0, 1.0, 0.0, 0.0),vec4(normalize(cross(CAMERA_MATRIX[0].xyz, vec3(0.0, 1.0, 0.0))),0.0),WORLD_MATRIX[3]);\n";
if (flags[FLAG_BILLBOARD_KEEP_SCALE]) {
code += "\tMODELVIEW_MATRIX = MODELVIEW_MATRIX * mat4(vec4(length(WORLD_MATRIX[0].xyz), 0.0, 0.0, 0.0),vec4(0.0, 1.0, 0.0, 0.0),vec4(0.0, 0.0, length(WORLD_MATRIX[2].xyz), 0.0), vec4(0.0, 0.0, 0.0, 1.0));\n";
} else {
code += "\tMODELVIEW_MATRIX = MODELVIEW_MATRIX * mat4(vec4(1.0, 0.0, 0.0, 0.0),vec4(0.0, 1.0/length(WORLD_MATRIX[1].xyz), 0.0, 0.0), vec4(0.0, 0.0, 1.0, 0.0),vec4(0.0, 0.0, 0.0 ,1.0));\n";
code += "\tMODELVIEW_MATRIX = MODELVIEW_MATRIX * mat4(vec4(length(WORLD_MATRIX[0].xyz), 0.0, 0.0, 0.0),vec4(0.0, length(WORLD_MATRIX[1].xyz), 0.0, 0.0),vec4(0.0, 0.0, length(WORLD_MATRIX[2].xyz), 0.0),vec4(0.0, 0.0, 0.0, 1.0));\n";
}
} break;
case BILLBOARD_PARTICLES: {