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[core] Use separate attribute component for line normals

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Broadcom GPUs don't cope well with using the least significant bit for this.
This commit is contained in:
John Firebaugh
2017-08-01 12:22:16 -07:00
parent 33407591f5
commit 822df3dd51
11 changed files with 47 additions and 46 deletions
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19
src/mbgl/shaders/line_pattern.cpp
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@@ -23,7 +23,7 @@ const char* line_pattern::vertexSource = R"MBGL_SHADER(
// Retina devices need a smaller distance to avoid aliasing.
#define ANTIALIASING 1.0 / DEVICE_PIXEL_RATIO / 2.0
attribute vec2 a_pos;
attribute vec3 a_pos_normal;
attribute vec4 a_data;
uniform mat4 u_matrix;
@@ -119,19 +119,21 @@ void main() {
float a_direction = mod(a_data.z, 4.0) - 1.0;
float a_linesofar = (floor(a_data.z / 4.0) + a_data.w * 64.0) * LINE_DISTANCE_SCALE;
// We store the texture normals in the most insignificant bit
// transform y so that 0 => -1 and 1 => 1
vec2 pos = a_pos_normal.xy;
// transform y normal so that 0 => -1 and 1 => 1
// In the texture normal, x is 0 if the normal points straight up/down and 1 if it's a round cap
// y is 1 if the normal points up, and -1 if it points down
mediump vec2 normal = mod(a_pos, 2.0);
mediump vec2 normal = unpack_float(a_pos_normal.z);
normal.y = sign(normal.y - 0.5);
v_normal = normal;
// these transformations used to be applied in the JS and native code bases.
// moved them into the shader for clarity and simplicity.
// these transformations used to be applied in the JS and native code bases.
// moved them into the shader for clarity and simplicity.
gapwidth = gapwidth / 2.0;
float halfwidth = width / 2.0;
offset = -1.0 * offset;
offset = -1.0 * offset;
float inset = gapwidth + (gapwidth > 0.0 ? ANTIALIASING : 0.0);
float outset = gapwidth + halfwidth * (gapwidth > 0.0 ? 2.0 : 1.0) + ANTIALIASING;
@@ -148,9 +150,6 @@ void main() {
mediump float t = 1.0 - abs(u);
mediump vec2 offset2 = offset * a_extrude * scale * normal.y * mat2(t, -u, u, t);
// Remove the texture normal bit to get the position
vec2 pos = floor(a_pos * 0.5);
vec4 projected_extrude = u_matrix * vec4(dist / u_ratio, 0.0, 0.0);
gl_Position = u_matrix * vec4(pos + offset2 / u_ratio, 0.0, 1.0) + projected_extrude;