diff options
| author | Eric Anholt <eric@anholt.net> | 2010-02-04 23:47:33 -0800 |
|---|---|---|
| committer | Eric Anholt <eric@anholt.net> | 2010-02-04 23:47:33 -0800 |
| commit | 6708bc0593a649d083ede429ae73f06691edc018 (patch) | |
| tree | 9c115f9fdabf314a54d36905a70d16748c5b5d2a | |
| parent | e426cdd56973ff1114dac5e8b1130180d43631b0 (diff) | |
[gl] When filling a gradient texture, multiply alpha after interpolating.
Fixes gradient-alpha testcase.
| -rw-r--r-- | src/cairo-gl-surface.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/src/cairo-gl-surface.c b/src/cairo-gl-surface.c index a0634a97..91686ea7 100644 --- a/src/cairo-gl-surface.c +++ b/src/cairo-gl-surface.c @@ -980,10 +980,11 @@ lerp_and_set_color (GLubyte *color, double r1, double g1, double b1, double a1) { double alpha = (t - t0) / (t1 - t0); - color[0] = ((1.0 - alpha) * b0 + alpha * b1) * 255.0; - color[1] = ((1.0 - alpha) * g0 + alpha * g1) * 255.0; - color[2] = ((1.0 - alpha) * r0 + alpha * r1) * 255.0; - color[3] = ((1.0 - alpha) * a0 + alpha * a1) * 255.0; + double a = ((1.0 - alpha) * a0 + alpha * a1); + color[0] = ((1.0 - alpha) * b0 + alpha * b1) * a * 255.0; + color[1] = ((1.0 - alpha) * g0 + alpha * g1) * a * 255.0; + color[2] = ((1.0 - alpha) * r0 + alpha * r1) * a * 255.0; + color[3] = a * 255.0; } static void @@ -1025,9 +1026,6 @@ _cairo_gl_create_gradient_texture (const cairo_gl_context_t *ctx, cairo_pattern_get_color_stop_rgba (&pattern->base, i, &offset, &r, &g, &b, &a); - r = r * a; - g = g * a; - b = b * a; stop_index = (stops[i].offset - *first_offset) / delta_offsets * tex_width; if (stop_index == tex_width) stop_index = tex_width - 1; @@ -1036,7 +1034,7 @@ _cairo_gl_create_gradient_texture (const cairo_gl_context_t *ctx, lerp_and_set_color (color, (stops[i - 1].offset - *first_offset) / delta_offsets, (stops[i].offset - *first_offset) / delta_offsets, - (j + 0.5) / tex_width, + (float)j / tex_width, prev_r, prev_g, prev_b, prev_a, r, g, b, a); ++j; @@ -1044,9 +1042,9 @@ _cairo_gl_create_gradient_texture (const cairo_gl_context_t *ctx, /* This is the exact texel for this stop; just set it. */ color = data + j * 4; - color[0] = b * 255.0; - color[1] = g * 255.0; - color[2] = r * 255.0; + color[0] = b * a * 255.0; + color[1] = g * a * 255.0; + color[2] = r * a * 255.0; color[3] = a * 255.0; ++j; |