diff options
Diffstat (limited to 'dom/canvas/test/webgl-conf/checkout/conformance/ogles/GL/acos/acos_float_vert_xvary_ref.vert')
-rw-r--r-- | dom/canvas/test/webgl-conf/checkout/conformance/ogles/GL/acos/acos_float_vert_xvary_ref.vert | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/dom/canvas/test/webgl-conf/checkout/conformance/ogles/GL/acos/acos_float_vert_xvary_ref.vert b/dom/canvas/test/webgl-conf/checkout/conformance/ogles/GL/acos/acos_float_vert_xvary_ref.vert new file mode 100644 index 0000000000..a18618539f --- /dev/null +++ b/dom/canvas/test/webgl-conf/checkout/conformance/ogles/GL/acos/acos_float_vert_xvary_ref.vert @@ -0,0 +1,41 @@ + +/* +Copyright (c) 2019 The Khronos Group Inc. +Use of this source code is governed by an MIT-style license that can be +found in the LICENSE.txt file. +*/ + + +attribute vec4 gtf_Vertex; +attribute vec4 gtf_Color; +uniform mat4 gtf_ModelViewProjectionMatrix; +varying vec4 color; + +void main (void) +{ + const float M_PI = 3.14159265358979323846; + float c = 2.0 * (gtf_Color.r - 0.5); + + float acos_c = 0.0; + float scale = 1.0; + float sign = 1.0; + + // pow can't handle negative numbers so take advantage of symmetry + if(c < 0.0) + { + sign = -1.0; + c *= -1.0; + } + + // Taylors series expansion for acos + // 1000/2 iterations necessary to get the accuracy with this method + for(int i = 1; i < 1000; i += 2) + { + acos_c += scale * pow(c, float(i)) / float(i); + scale *= float(i) / float(i + 1); + } + acos_c = M_PI / 2.0 - sign * acos_c; + + color = vec4(acos_c / M_PI, 0.0, 0.0, 1.0); + gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex; +} |