diff options
Diffstat (limited to 'source/blender/draw/engines/overlay/shaders/grid_frag.glsl')
| -rw-r--r-- | source/blender/draw/engines/overlay/shaders/grid_frag.glsl | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/source/blender/draw/engines/overlay/shaders/grid_frag.glsl b/source/blender/draw/engines/overlay/shaders/grid_frag.glsl new file mode 100644 index 00000000000..db845c7f1dd --- /dev/null +++ b/source/blender/draw/engines/overlay/shaders/grid_frag.glsl @@ -0,0 +1,248 @@ + +/* Infinite grid + * Author: Clément Foucault */ + +/* We use the normalized local position to avoid precision + * loss during interpolation. */ +in vec3 local_pos; + +out vec4 FragColor; + +uniform vec3 planeAxes; +uniform float gridDistance; +uniform float meshSize; +uniform float lineKernel = 0.0; +uniform sampler2D depthBuffer; + +#define cameraPos (ViewMatrixInverse[3].xyz) + +uniform int gridFlag; + +#define STEPS_LEN 8 +uniform float gridSteps[STEPS_LEN] = float[](0.001, 0.01, 0.1, 1.0, 10.0, 100.0, 1000.0, 10000.0); + +#define AXIS_X (1 << 0) +#define AXIS_Y (1 << 1) +#define AXIS_Z (1 << 2) +#define GRID (1 << 3) +#define PLANE_XY (1 << 4) +#define PLANE_XZ (1 << 5) +#define PLANE_YZ (1 << 6) +#define GRID_BACK (1 << 9) /* grid is behind objects */ + +#define M_1_SQRTPI 0.5641895835477563 /* 1/sqrt(pi) */ + +/** + * We want to know how much a pixel is covered by a line. + * We replace the square pixel with acircle of the same area and try to find the intersection area. + * The area we search is the circular segment. https://en.wikipedia.org/wiki/Circular_segment + * The formula for the area uses inverse trig function and is quite complexe. Instead, + * we approximate it by using the smoothstep function and a 1.05 factor to the disc radius. + */ +#define DISC_RADIUS (M_1_SQRTPI * 1.05) +#define GRID_LINE_SMOOTH_START (0.5 - DISC_RADIUS) +#define GRID_LINE_SMOOTH_END (0.5 + DISC_RADIUS) + +float get_grid(vec2 co, vec2 fwidthCos, float grid_size) +{ + float half_size = grid_size / 2.0; + /* triangular wave pattern, amplitude is [0, half_size] */ + vec2 grid_domain = abs(mod(co + half_size, grid_size) - half_size); + /* modulate by the absolute rate of change of the coordinates + * (make lines have the same width under perspective) */ + grid_domain /= fwidthCos; + + /* collapse waves */ + float line_dist = min(grid_domain.x, grid_domain.y); + + return 1.0 - smoothstep(GRID_LINE_SMOOTH_START, GRID_LINE_SMOOTH_END, line_dist - lineKernel); +} + +vec3 get_axes(vec3 co, vec3 fwidthCos, float line_size) +{ + vec3 axes_domain = abs(co); + /* modulate by the absolute rate of change of the coordinates + * (make line have the same width under perspective) */ + axes_domain /= fwidthCos; + + return 1.0 - smoothstep(GRID_LINE_SMOOTH_START, + GRID_LINE_SMOOTH_END, + axes_domain - (line_size + lineKernel)); +} + +#define linearstep(p0, p1, v) (clamp(((v) - (p0)) / abs((p1) - (p0)), 0.0, 1.0)) + +void main() +{ + vec3 wPos = local_pos * meshSize; + vec3 dFdxPos = dFdx(wPos); + vec3 dFdyPos = dFdy(wPos); + vec3 fwidthPos = abs(dFdxPos) + abs(dFdyPos); + wPos += cameraPos * planeAxes; + + float dist, fade; + /* if persp */ + if (ProjectionMatrix[3][3] == 0.0) { + vec3 viewvec = cameraPos - wPos; + dist = length(viewvec); + viewvec /= dist; + + float angle; + if ((gridFlag & PLANE_XZ) != 0) { + angle = viewvec.y; + } + else if ((gridFlag & PLANE_YZ) != 0) { + angle = viewvec.x; + } + else { + angle = viewvec.z; + } + + angle = 1.0 - abs(angle); + angle *= angle; + fade = 1.0 - angle * angle; + fade *= 1.0 - smoothstep(0.0, gridDistance, dist - gridDistance); + } + else { + dist = abs(gl_FragCoord.z * 2.0 - 1.0); + fade = 1.0 - smoothstep(0.0, 0.5, dist - 0.5); + dist = 1.0; /* avoid branch after */ + + if ((gridFlag & PLANE_XY) != 0) { + float angle = 1.0 - abs(ViewMatrixInverse[2].z); + dist = 1.0 + angle * 2.0; + angle *= angle; + fade *= 1.0 - angle * angle; + } + } + + if ((gridFlag & GRID) != 0) { + /* Using `max(dot(dFdxPos, screenVecs[0]), dot(dFdyPos, screenVecs[1]))` + * would be more accurate, but not really necessary. */ + float grid_res = dot(dFdxPos, screenVecs[0].xyz); + + /* The gride begins to appear when it comprises 4 pixels */ + grid_res *= 4; + + /* from biggest to smallest */ + vec4 scale; +#if 0 + int step_id = 0; + scale[0] = 0.0; + scale[1] = gridSteps[0]; + while (scale[1] < grid_res && step_id != STEPS_LEN - 1) { + scale[0] = scale[1]; + scale[1] = gridSteps[++step_id]; + } + scale[2] = gridSteps[min(step_id + 1, STEPS_LEN - 1)]; + scale[3] = gridSteps[min(step_id + 2, STEPS_LEN - 1)]; +#else + /* For more efficiency, unroll the loop above. */ + if (gridSteps[0] > grid_res) { + scale = vec4(0.0, gridSteps[0], gridSteps[1], gridSteps[2]); + } + else if (gridSteps[1] > grid_res) { + scale = vec4(gridSteps[0], gridSteps[1], gridSteps[2], gridSteps[3]); + } + else if (gridSteps[2] > grid_res) { + scale = vec4(gridSteps[1], gridSteps[2], gridSteps[3], gridSteps[4]); + } + else if (gridSteps[3] > grid_res) { + scale = vec4(gridSteps[2], gridSteps[3], gridSteps[4], gridSteps[5]); + } + else if (gridSteps[4] > grid_res) { + scale = vec4(gridSteps[3], gridSteps[4], gridSteps[5], gridSteps[6]); + } + else if (gridSteps[5] > grid_res) { + scale = vec4(gridSteps[4], gridSteps[5], gridSteps[6], gridSteps[7]); + } + else if (gridSteps[6] > grid_res) { + scale = vec4(gridSteps[5], gridSteps[6], gridSteps[7], gridSteps[7]); + } + else { + scale = vec4(gridSteps[6], gridSteps[7], gridSteps[7], gridSteps[7]); + } +#endif + float blend = 1.0 - linearstep(scale[0], scale[1], grid_res); + blend = blend * blend * blend; + + vec2 grid_pos, grid_fwidth; + if ((gridFlag & PLANE_XZ) != 0) { + grid_pos = wPos.xz; + grid_fwidth = fwidthPos.xz; + } + else if ((gridFlag & PLANE_YZ) != 0) { + grid_pos = wPos.yz; + grid_fwidth = fwidthPos.yz; + } + else { + grid_pos = wPos.xy; + grid_fwidth = fwidthPos.xy; + } + + float gridA = get_grid(grid_pos, grid_fwidth, scale[1]); + float gridB = get_grid(grid_pos, grid_fwidth, scale[2]); + float gridC = get_grid(grid_pos, grid_fwidth, scale[3]); + + FragColor = colorGrid; + FragColor.a *= gridA * blend; + FragColor = mix(FragColor, mix(colorGrid, colorGridEmphasise, blend), gridB); + FragColor = mix(FragColor, colorGridEmphasise, gridC); + } + else { + FragColor = vec4(colorGrid.rgb, 0.0); + } + + if ((gridFlag & (AXIS_X | AXIS_Y | AXIS_Z)) != 0) { + /* Setup axes 'domains' */ + vec3 axes_dist, axes_fwidth; + + if ((gridFlag & AXIS_X) != 0) { + axes_dist.x = dot(wPos.yz, planeAxes.yz); + axes_fwidth.x = dot(fwidthPos.yz, planeAxes.yz); + } + if ((gridFlag & AXIS_Y) != 0) { + axes_dist.y = dot(wPos.xz, planeAxes.xz); + axes_fwidth.y = dot(fwidthPos.xz, planeAxes.xz); + } + if ((gridFlag & AXIS_Z) != 0) { + axes_dist.z = dot(wPos.xy, planeAxes.xy); + axes_fwidth.z = dot(fwidthPos.xy, planeAxes.xy); + } + + /* Computing all axes at once using vec3 */ + vec3 axes = get_axes(axes_dist, axes_fwidth, 0.1); + + if ((gridFlag & AXIS_X) != 0) { + FragColor.a = max(FragColor.a, axes.x); + FragColor.rgb = (axes.x < 1e-8) ? FragColor.rgb : colorGridAxisX.rgb; + } + if ((gridFlag & AXIS_Y) != 0) { + FragColor.a = max(FragColor.a, axes.y); + FragColor.rgb = (axes.y < 1e-8) ? FragColor.rgb : colorGridAxisY.rgb; + } + if ((gridFlag & AXIS_Z) != 0) { + FragColor.a = max(FragColor.a, axes.z); + FragColor.rgb = (axes.z < 1e-8) ? FragColor.rgb : colorGridAxisZ.rgb; + } + } + + /* Add a small bias so the grid will always + * be on top of a mesh with the same depth. */ + float grid_depth = gl_FragCoord.z - 6e-8 - fwidth(gl_FragCoord.z); + float scene_depth = texelFetch(depthBuffer, ivec2(gl_FragCoord.xy), 0).r; + if ((gridFlag & GRID_BACK) != 0) { + fade *= (scene_depth == 1.0) ? 1.0 : 0.0; + } + else { + /* Manual, non hard, depth test: + * Progressively fade the grid below occluders + * (avoids popping visuals due to depth buffer precision) */ + /* Harder settings tend to flicker more, + * but have less "see through" appearance. */ + const float test_hardness = 1e7; + fade *= 1.0 - clamp((grid_depth - scene_depth) * test_hardness, 0.0, 1.0); + } + + FragColor.a *= fade; +} |